- "Thea Queen was also weak and no matter what it takes I will be strong."
- —Thea in her letter to Roy Harper[src]
Thea Dearden Queen (born January 21, 1995) is the daughter of Malcolm Merlyn and the late Moira Queen, the step-daughter of the late Robert Queen (though treated unquestionably as his daughter throughout his life), the ex-step-daughter of Walter Steele, the maternal younger half-sister of Oliver Queen, the paternal younger half-sister of the late Tommy Merlyn, the aunt of Oliver's child, and the sister-in-law of Nyssa al Ghul. Thea is also the ex-girlfriend of Roy Harper. After learning how to fight from Malcolm, Thea became a vigilante and member of Team Arrow using her half-brother's nickname for her, Speedy, as her codename.
Thea was born on January 21, 1995 to Malcolm Merlyn and Moira Queen. Though Malcolm was unaware that Thea was his daughter as Thea herself was unaware that Malcolm was her father. Robert Queen however was aware but still loved Thea like his own. When Thea was a child she fell off her horse and was hospitalized. Thea (it is insinuated) idolized Oliver as a child. They used to be close and, according to Oliver, he used to chase after her when she was younger, thus giving her the nickname, "Speedy". When her father and brother (who were in reality her step-father and maternal half-brother) were both presumed dead, Thea felt alone and disconnected from the world. She fell into a life of drugs and partying to fill the void left by her father and brother.
Oliver Queen's return
Thea was one of the first people to welcome Oliver home with open arms. Though she is later surprised and disappointed when Oliver expresses his unhappiness with her party lifestyle, which Oliver himself used to lead.
Thea was brought home by the police after a night of drunken partying that led to breaking and entering a shop. Despite being grounded, she partied at the nightclub Poison, where she bumped into Oliver, and the two had an argument. Thea disclosed to Oliver that Laurel and Tommy had been sleeping together in his absence and stumbled off. Thea toned down her wild behavior towards the end of the episode, having a mother-daughter moment with Moira, and appearing at the Unidac auction.
Thea bonded with Oliver while they discussed Laurel, and how Oliver could get back into her "good-books" again.
Thea and her family were worried for Oliver after multiple charges were brought against him by Sergeant Quentin Lance. Thea showed how much her brother's absence had affected her when she told Oliver that "she couldn't lose him again". Oliver reassured her at the end that she wouldn't.
Thea was shown to have a crush on Tommy, after he came asking her for romantic advice. Things, however, got very awkward when she realized he meant Laurel instead of her. Thea ended up getting drunk at the CNRI benefit, and Tommy took her home.
Thea called Oliver to remind him that he was supposed to have lunch with Moira, telling him to "bite the bullet and have a cobb salad with the woman". Later on she was with Moira at the hospital and later seen telling Oliver off for leaving Moira and going after the shooter. Thea stayed in that night with Moira after Oliver told her he had a business meeting, talking to Moira about how she wished that Oliver wouldn't lie and would tell them what was wrong. Thea then spoke to Oliver, saying that he shouldn't keep what happened on the island a secret, and that he should tell someone about what happened.
Thea asked Walter for a lift to school, commenting that they could just buy her a convertible to save them the trouble.
Oliver talked to Thea about why their lack of Christmas decorations, and she explained how they hadn't really celebrated Christmas since Oliver and Robert had disappeared. Thea was later seen at Big Belly Burger with Oliver, discussing why there was no Christmas Party when Thea's friend Shane showed up. Oliver later walked in on Thea and Shane at the Christmas Party and caught them making out with some clothes off. Oliver told the boy, "Hit the road". She later admitted she was being a "bitch", when Oliver was injured, at the hospital.
Thea was with Oliver, going through movies to watch, telling him how Moira was acting the same way as when Robert and Oliver disappeared. Thea later tried to convince her mother to leave her room and go out with her. She later commentsedon why Oliver was smiling, saying that his club burnt down.
Thea believed that her mother was having an affair with Malcolm Merlyn. On her 18th birthday, she was involved in a car crash and was taken to the hospital. Oliver later discovered that Thea crashed because a drug called Vertigo was in her system. Because she was driving under the influence of drugs, she was arrested.
Due to the rampant use of Vertigo in Starling City, the judge overseeing Thea's trial decided that the best way to discourage the drug's use was to sentence Thea to hard time, by showing that not even the rich can escape the law. Oliver decided to take down The Count so as to take heat off her. He also talked to Laurel about getting her father to use his connections to help Thea. Detective Quentin Lance was able to get Thea a deal where she had to work community service for 500 hours, and be under the watch of a guardian, Laurel. The plan was for her to work at CNRI. Thea refused the deal just to spite her mother, who she thought was cheating on Walter and cheated on her father, as well. Oliver decided to convince her, revealing that their father cheated on their mother. Thea forgave her mother when she overheard her mother confirm what Oliver revealed to her about their father. She then decided to take Laurel's offer and work with her.
Thea was at CNRI with Laurel, complaining about how long she had left to work, hearing about how Cyrus Vanch was being released. She saw herself as a "court-ordered slave", and asked "how [her 500 hours of community service was] not cruel and unusual punishment".
Thea was seen at the end of the episode, stating that she had been trying to ring Oliver all night as Moira was attacked by the vigilante.
When Thea went to see Roy again he brushed her off, but saved Thea from some thugs. In doing so, he was stabbed, and Thea had to take him to the hospital where he had to get a shot, which Roy was scared of. She told him to take his mind off of it, to which he responded that he didn't like sharp things. When the doctor gave Roy the shot, she kissed Roy to distract him from it.
She and Roy were in a romantic relationship, and Thea saw Roy being kidnapped by the Savior. When he was interrogated, she was watching and Oliver went up to her. She was crying, and Oliver promised that Roy would not die.
Thea continued to help Roy find the Hood but Oliver told Roy not to and Thea agreed with him but Roy didn't, leading to them briefly splitting.
After hearing Moira's revelations, she went to the Glades to help save Roy. She threw an empty glass bottle at a gang member who was about to shoot Roy. When Roy saw people on a bus trapped, Thea told Roy not to help because the device could go off any second. Roy told her that he couldn't leave anyone behind and told Thea to get out of the Glades.
After the Undertaking
5 months after the earthquake, Thea got her act together taking over Oliver's role as owner of Verdant, and still in a relationship with Roy Harper. However, they tend to fight due to Roy trying to fill in the Hood's role. When Oliver came back Thea was happy to see her brother again, who was impressed by how much his sister changed. Thea shut him down when Oliver attempted to persuade her to visit Moira in prison. Later Roy also made the same attempt, only to be shut down as well. When Verdant later got attacked by the Hoods, looking for Oliver, Roy made an attempt to fight the attackers, to no avail with the Hoods kidnapping Thea in the process. While in captivity, when the Hoods argued what to do with Thea, Thea realized that Moira was a victim of circumstances and that she had no choice but to follow Malcolm due to her fear of him. When one of the Hoods decided to kill Thea, Oliver, as the Hood, managed to save her. Later Thea visited Moira in prison telling her about her near death experience, and reconciled with her mother.
After Roy was arrested during his self attempt to fend off the hijackers, Thea gave Roy a ultimatum, which he later accepted, telling her that he chose her and was done being the hero, though he was actually lying.
During Moira's trial both Oliver and Thea were stunned, when the A.D.A Adam Donner wanted to seek the death penalty for Moira. Oliver later encouraged Thea that they were both going to help their mother to fight for her life. Later they both watched the news of the Lances' kidnapping.
During the "cash for guns" event, Thea met Sin. When the events were crashed by The Mayor, both Roy and Thea evaded getting shot by hiding behind a car; when Sin as shot, Thea went to get help for her. Later both Roy and Thea stayed in the hospital by Sin's side. Sin commented to Thea that she was dating a moron and Thea agreed. Sin admitted to Roy that she liked Thea.
Thea was furious at her mother when she decides to take the deal that Adam offered for her, she and Oliver encouraged her to fight for her life, later when Thea and Oliver visited her again, they assured her that she will not lose them and they will stick by her no matter what secret Moira is hiding, which led Moira to agree to refuse the deal.
Thea went to the police station to bail Roy out of prison, Later when Moira's lawyer visited Thea in the club telling her the her relationship with Roy a known felon is hurting Moira's case, which promoted Thea to break up him, Later when Thea was visiting her mother, surprised to see Roy is there, telling Thea that she has flourished during last year and it had a lot to do with Roy assuring that her personal life is not going to effect her case, bringing Roy and Thea back together.
Thea, Oliver, and Roy were present during Moira's trial's opening. When Thea was brought to the stand Adam Donner questioned Thea for not visiting her mother. He even told her that she she felt angry at her mother which was the reason that it took long time for Thea to visit her mother. Later in the club Roy who notices Thea's anger bought her boxing gloves and told her to punch him as a release. During the second half of the trail when Moira refused to testify, both her children questioned her reasons which led Moira to admit having an affair with Malcolm much to Thea's dismay. Later Thea and Oliver await for the verdict when Oliver ran off to Count Vertigo much to Thea's surprise. After Oliver came back to the court Thea and Oliver were overjoyed when Moira was found not guilty and acquitted of all charges.
Thea and Oliver welcomed Moira home before heading out with Roy to meet Sin, Roy was surprised that Thea, not only approve but also decided to join Roy and Sin search for Sin's missing friend, Max. The three later head to his house to investigate only to find out that his disappearance related to Sebastian Blood, during Moira's party, when Roy received a call from Sin about her friend, Roy left the party and insisted Thea to stay with her mother. After the party Moira was about to tell Thea the truth about her parentage but changed her mind and settled for saying that she loves her.
After Roy got shot with an arrow, Thea locked herself in her room along with Sin which made a concerned Moira who asked Oliver to check on her, upon the finding out the truth Oliver removed the arrow from Roy's leg and warned the three of them, to stay out of trouble. Sin asked Thea if she is gonna let it go, which she refused stating that she is doing things her way. Later both Thea and Sin seek Laurel's help in regard Max's case, later when Laurel came back with information regarding the blood drive, telling them that that they can't get a warrant to investigate more regarding whether Max was on drugs or not. After Roy woke up in Thea's room, Thea and Sin are seen rushing in to see him, concerned that he was chasing down the Arrow.
Thea was present during Oliver speech about Blood, which she joked about Oliver friendship with Blood, due to his relationship with Laurel. Oliver then changed the subject asking Thea about Roy's condition, which she joked about how Roy came to work on time. Later when Thea came to check on Roy, she noticed him acting strange when she confronted him he pushed her off, but admitted that she is the one who is helping him getting through the hard time which led the two to make out, but Roy was injured by a falling glass, later during Blood's Unity Rally, when it was attacked by "Shrapnel" Thea witnessed Roy save Moira, which she confronted him later about it but didn't give her a straight answer leaving Thea confused.
Thea refused to talk to Roy due to him lying about what is going on with him. Later she helped Sin to pick a dress for her "date" with the Starling Slasher whom Roy later put in a hospital. Afterwards Thea came to the hospital after Sin called her, Thea told Roy she is not judging him, and that she is there for him which led Roy to break down and run away. Later in the club Thea confide in Oliver about her issues with Roy.
In "Time of Death",
In "The Promise",
Thea received a bracelet from Roy at Verdant. The day after, at Verdant, Roy went up to Thea and said that he wanted to break up with her, making her shocked and confused. Thea realizes that Roy is going through something and wants to be there for him. She went up the stairs and caught Roy kissing another woman. She was hurt by seeing this and threw the bracelet she got from him on the floor and walked away. During the evening, she told Oliver what she saw. Thea told Oliver that everyone is lying to her and Oliver is the only one she can trust. When she was heading home, Slade's car stopped and he offered her a ride home, which she accepted.
Thea was kidnapped by Slade Wilson and is told by him that Malcolm Merlyn is her biological father. The news makes her break down in shock and tears, and thus wrecking the relationship between her, Oliver and Moira.
A furious Thea refuses to sign a form to protect the Queen family's assets from Isabel Rochev, and tells Oliver that she's irreparably damaged because she is the daughter of two mass murderers. Later, she angrily moves out of the Queen mansion and abandons her family. She knows her refusal to sign the form would likely bankrupt her family and leave those that work for them unemployed but she is too focused on her own problems to care.
Thea continued to a keep distance from her family, even trying to keep her mother from doing her rally at the club which Thea was reluctant gone through it since she signed a contract, Later in the club Thea was put under Diggle's protection by Oliver much to her annoyance, they talked about family and she should give them a second chance when the news about Roy attacking a polices officer, Thea met up with Sin who told her about Roy's incident, later during the rally Thea made a speech to lure Roy in which worked Roy attacked the rally when Thea tried to get though Roy, he ended up attacking her however she was saved by the Canary and the Arrow, who assured her that they gonna help Roy. Later when the Queen family talked on their way home Moira said they need to start over, when Moira was about to tell them something about Malcolm, their limo got crashed into, when Oliver woke up at the sight of Moira and Thea tied up with Slade forcing him to choose between the two, when Slade was about to kill Thea, Moira stood up and offered herself, Moira's last words were "Thea I love you, close your eyes baby". Slade kills Moira with a sword much to Thea's horror, after Slade taunts Oliver he unties Thea which she rushed to her mothers side.
Thea attended her mother's funeral and was visibly upset that Oliver was unable to attend. Isabel later came to her club to reclaim it, as it was built upon property owned by Queens Consolidated, then she told Oliver that she didn't want to give Isabel the satisfaction of kicking her out of her own home and that she needed a change of scenery. Oliver agreed and let her go. Thea packed her things in a backpack, took one more look around her home, ignoring a call from Walter, she left. Just as she was about to board the train, one of Slade's agents attacked the station.
Thea attempted to flee but was saved by her biological father, Malcolm Merlyn. Malcolm tried to talk to her but Thea ran off, wanting nothing to do with him. They were both attacked, but Malcolm was able to subdue the mirakuru soldier. Thea grabbed a gun off the ground near a dead cop and shot Malcolm as he tried to reason with her.
Malcolm was shown to still be alive and reiterated that he needed Thea by his side, going as far as to compare her qualities to everything his own son lacked. Thea left and reunited herself with Roy. Deciding to help everyone else, Roy told her to stay at his house and pack her things. Upon discovering that Roy was secretly the Arrow's sidekick, which he had kept from her all along, she ultimately decided to start her life over. Leaving a goodbye note to Roy, Thea decided to go with her father and leaves Starling City and her family behind, with no intentions of coming back.
Training with Malcolm Merlyn
When Malcolm brought Thea to Corto Maltese, he began to train her, teaching her concepts such as "Pain is inevitable, but suffering is optional" by pouring boiling water over her hand. Thea attempted to resist the pain but soon placed her hand in the bowl of cool water below. Malcolm then decided to train her the same way he was trained. Thea was then beaten and kicked by Malcolm several times, before she pulled a sword on Malcolm, to which he stated they could begin.
Somewhere during this six months he drugged her with a poison which made her obey his commands without remembering it. The two of them went with a plane towards Starling City. While being drugged Malcolm made her kill Sara Lance by shooting her in the chest with arrows. The two then returned to Corto Maltese but Thea had no memory of murdering Sara. She trained further and her father was proud of her skills in combat and she proudly addressed him as "dad".
While working at a cafe in Corto Maltese she received a surprise visit from Oliver. She asked how Oliver found her and later apologized for lying and told Oliver she just needed space. She soon realized that Oliver was there to convince her to go home but quickly shot him down and said she was never go back to Starling City. Thea then was visited by Roy, who apologized to her for all the lies he had told. When Roy asked if she felt lonely in Corto Maltese, she told him that was the best part, as no one knew her or could lie to her. Late, Thea received another visit from her half-brother, who decided to reveal to her the truth about how their dad made it to a life boat after the Gambit went down, eventually sacrificing himself when they ran out of resources. Oliver asked Thea to reconsider her decision on staying in Corto Maltese. Thea requested to her father to go back to Starling City but Malcolm believed that she hadn't gone as far as he'd thought. They got in to a quick duel where Thea was disarmed, however she quickly disarmed her father, therefore proving that she was ready to leave. At the airport, when coffee was spilt on her hand, she hardly flinched, much to Oliver's surprise.
Returning to Starling City
Thea had dinner with Oliver and told him about reopening Verdant with the help of investors. Roy would approach her later asking for help to which she asked which shade of green he liked best. When she left the club with Roy, Nyssa confronted them, hit Roy with a tranquilizer dart when he tried to protect her. Thea allowed Nyssa to kidnap her. Nyssa used Thea to lure Malcolm to his death, but is rescued by her brother, the Arrow. She later hired Roy as an assistant manager. Malcolm called to check up on her and she thanked him for taking care of her, then he states that he had promised he will never let anyone hurt her.
Thea is visited by Oliver at her new apartment. Oliver was furious learning that she used Malcolm's money as he believed that it was going to draw Malcolm out. Oliver then realized Thea had no investors for the club also and told her to not use the money. Thea proceeded to tell Oliver that the movers are coming tomorrow so he could come with popcorn or not stop by at all. The following day, Oliver arrived with popcorn and Thea invited Oliver to live with her. Oliver accepted and the two watched TV and shared the popcorn.
Re-opening her club Thea holds an audition for DJ. A guy named Chase comes in and tells everyone to go home as he is certain he is the right man for the job. Thea tells him he can do audition like everyone else after which he leaves. During the grand re-opening Carrie Cutter walked past her while she was disappointed by the performance of the DJ. Thea told him to leave, after which Chase offered to help her. After some negotiation, he started and the crowd began to dance. After the night was over, she and Chase shared a kiss and he let her keep the money as a gift for her grand opening.  Thea later walked down the street talking to Chase on the phone telling him their kiss didn't mean anything, but was distracted by a bolt of lightning moving past her. She later gave drinks to Roy and Felicity with their friends Cisco Ramon and Caitlin Snow, where Cisco expressed interest in her but quickly moved on after learning she was Roy's ex-girlfriend and Oliver's sister. 
Thea visited Moira's grave and saw Laurel talking to Sara's grave. She asked her why she is here as she thinks Sara is alive. A emotional Laurel tells Thea that Sara was with dangerous people and has been killed and that she is buried here. Laurel makes her promise not to tell Quintin about it. At the appartment she bought in an enormous christmas tree, Oliver comes in and she tells him that the smaller the family the bigger the tree. Oliver says he knows Malcolm was with her at Corto Maltese, she avoids the subject and tells him he is one of the few family members she has left. Oliver asks her if she flew from Corto Maltese with Malcolm Merlyn. Thea says she did not and asks him to not make her choose between her father and Oliver. She later is decorating the christmas tree and hangs a picture of Moira in the tree. She then comes up with two stars with her and Oliver his name. Oliver (under the guise of the Arrow) lands on her balcony and breaks through her window. He demands to know where Malcolm Merlyn is. Thea feigns to be scared and then throws broken glass in his face. She kicked Oliver in the groin and threw multiple blows at him. However, he expertly dodged and parrids the hits, forcing Thea to distance herself and tell him to stay away from her and her father. She then escaped by jumping off the balcony. She contacted Malcolm and told him that the Arrow confronted her. She later lied to Oliver and told him the window was broken by a bird. Oliver told Thea that she did not know who Malcolm Merlyn was and that he did not love her, because he was incapable of it (hinting to making her kill Sara). She said she did not want to choose between the two of them. Oliver replied that he was not going to make her choose; there was nothing he would not do to protect her. Confused, she hugged him as she was unaware he was going to have a duel against Ra's al Ghul to save her. 
She continued her training with Malcolm who taught her to adapt to her situation and her opponent's. She mentioned she was worried about Oliver and Malcolm told her he would look into it. Malcolm later waited for her at her loft and told her that the city had become dangerous for them. He said they have to leave the city and never come back.
She met Chase at Verdant who came to get his stuff. He asked her if they were good as he started to think she was avoiding him. She said they were good but held him off when he talked about their shared kiss. Malcolm showed up in his car and said he expected her to pack and that they had to leave. Thea mentioned she wanted to know why. However Malcolm says she is not ready for the reason, Thea replied that then she is not ready to leave Starling City.
At her apartment Malcolm shows up and apologizes for what he said. He explains sharing the truth is sometime difficult. Malcolm explains to her that Ra's wants to kill him and his family for the undertaking and that he fell in with Ra's after the death of his wife.
Thea and Malcolm later speak again at the apartment. Malcolm asks if she is ready to leave and Thea says she will not leave. Thea explains he told her why they are in danger but asks why they have to leave if he will try to kill them anyway. She tells Malcolm he taught her not to be afraid and stand her ground. She says she learned to stand her ground and not give an inch in battle and that Ra's should be afraid of them. Malcolm seems moved and says they will stay.
When Thea was flirting with Chase, Oliver came to talk to her. He explained he needed to show her something and took her into the Arrowcave, revealing his identity as the Arrow. While Thea was initially angry for all of the times Oliver was lying and being a "Flake", she realized that he was saving people and not only accepted Oliver's life, but praised him for it. Oliver then addresses the fact that Malcolm knew of Oliver's dual identity and they needed to know in order to fight Ra's, but she was angry at her father for manipulating him. After a failed attempt to find Zytle, Oliver returned home and explained despite his hatred for Malcolm, they needed him to defeat Ra's, but Thea believes they can defeat him without her father. Back at the club, Thea and Roy, who was pleased by Thea knowing about their lives, talk about Malcolm's involvement and she prefers to keep him out of their lives. When Laurel was poisoned by Vertigo, Thea came inside, seeing what happened and when Oliver ordered her to wait outside, Roy stood up to him. Outside the club, Thea met up with Chase and they slept together in her apartment. When Chase poured them wine, Thea noticed an odd smell in the wine and explained wine was effective in covering the scent of poison. She attacked Chase, who effortlessly blocked her attack and revealed himself as an agent of the League. Roy saved Thea and Malcolm ambushed Chase, who killed himself when he had no way out. After Oliver defeated Vertigo, he raced over to comfort her and while she never asked to be a part of this, she relents to let Malcolm help, not forgetting who he is or what he has done. When Thea and Oliver left town, Roy asks if she was okay. She admits it will be a while before she can feel that way again and kissed Roy for saving her life. Oliver and Thea later arrive on Lian Yu, where Thea believed training there was too excessive.
While training on Lian Yu, Oliver discovered that Malcolm released Slade from the A.R.G.U.S. prison centre. He then informs Thea about it and tells her to go and get a gun from his father's grave. Unfortunately Slade shows up and goes after the both of them and manages to take them down. He then places them in the prison. luckily they manageed to open the cage door and escape. Oliver then tells Thea that she was the one who murdered Sara. As she grapples with the truth Slade arrives. The three of them fight, Thea manages to wound Slade with the gun which allows them to imprison him back into his cell. They then return to home and Thea confronts Malcolm by saying that she will train, fight and work with him but he is no longer her father.
Thea along with Oliver continued to train with Malcolm. She still struggled with the guilt over killing Sara and tells Laurel the truth. Laurel tells her that it isn't her fault and that she isn't the one responsible but asks why she would be associated with someone like Malcolm to which Thea replies to by revealing about the league coming after him as well as her and Oliver. Thea then contacted the League and made a deal to hand her father over to them. Nyssa and the League then showed up and manage to capture Malcolm (while he was fighting with Laurel). Thea then informs Oliver about what she did back at her loft. Oliver goes to Nanda Parbat to rescue Malcolm in order to stop Thea from losing her humanity once she realizes that she has sentenced her father to his death. Thea then confronts Nyssa (who Oliver manage to capture earlier) and tells her the truth about Sara's death. She then offers her a chance at revenge as she opens her cell door and hands her back her weapon.
Nyssa refused to believe Thea's confession, but Thea inforeds her in more detail about Sara's death and not wanting to help her father as she states that Malcolm drugged and brainwashed her with Vitura and how she shot three arrows into Sara's chest. Nyssa then informed her that there would be no justice in killing her and that this would all end with Malcolm's death. Suddenly Roy and Laurel enter and attack Nyssa (believing that she somehow escaped and was attacking Thea). After Nyssa is tranquillized and knocked out by Roy (who used a dart gun to take her down as she easily outmatched the latter of the two), Thea leaves. She then returns to her loft and discovers that Oliver along with Malcolm have both returned. Later on Laurel comes to visit and talks to Thea about all of this. After she leaves, Thea talks to Malcolm who was listening to their conversation. he then reveals that he knows she's holding a knife which surprised her. He then orders her to kill him but she declined. She then talks to Oliver about Malcolm as well as her mother and past. Later on, she then leaves and goes over to Roy's place. She asks if she can stay with him for a while and they begin to kiss.
Post-sex, she and Roy discussed running away together. The two then spotted the newscast about the Arrow. She is then seen Back at HQ when Oliver spoke over the phone with an angry Quentin Lance who wanted him to turn himself in. Oliver then apologized to everyone for putting them in this position, but Thea thought the blame was with Malcolm. Back at her club, Roy told her that while he shot the cops, part of him felt "relieved" that he might finally go to jail where he belongs. Oliver came in and apologized to Roy. Just then, the police broke down the doors and Oliver took off as they chased after him. They then discover that all of their assets have been frozen by Quentin so Oliver couldn't escape the city.
Thea visited Roy (who masqueraded as the Arrow), in the prison's visiting room at Iron Heights Prison. She was told by Roy everything was going to be fine. Thea returned to her loft, along with a commanding officer who both told Quentin Lance to back off as he and a squadron raided her loft for evidence to prove that Oliver is the Arrow in order to arrest him. Quentin then got a call and is informed about the failed attack on Roy at the prison which he then told Thea about. After Roy is supposedly killed in prison, Quentin went over to Thea's loft and consoled her. Oliver then showed up and Quentin informed him about it as well and then blamed him for Roy's death. Later, she looked at pictures of her and Roy on her cell as she drank wine. Suddenly Ra's al Ghul appeared which shocked her as she dropped her wine. Thea then stated that her brother is going to kill him but Ra's corrected her by saying that Oliver is going to beg him for mercy. Thea then threw a knife at him and tried to escape by making a run for the door. A brief fight occured as she tried to defend herself. Unfortunately he got the upper hand and smashed her through a nearby table. He then stabbed her in the chest and left. She was then left on the floor with her life hanging by a thread as she started to bleed out.
Oliver arrived at the apartment and immediately took her to the hospital, where it doesn't look like she'll survive the attack. Oliver, Malcolm, and his team take Thea to Nanda Parbat, where Thea is resurrected and healed from the Lazarus Pit (though she initially comes out mindlessly attacking Oliver until she's subdued). When she woke up, she appeared to have no memory of who Oliver was and looked to Malcolm for comfort. When Felicity's escape plan falls flat, Oliver helped them by using his control over the other assassins and told Thea to never forget that he loves her. The next day she woke up and regained her memory. As Malcolm recapped the events, she showed concern for Oliver's whereabouts.
Thea had dinner at Diggle's home along with Felicty, Lyla and their daughter Sara. John asked her how she felt since she was resurrected by a Lazarus Pit] and she responded by saying it felt weird but she's OK. Thea then stated that she missed her half-brother and blames herself for his transformation. Thea returned to the Arrowcave and talked to Felicity as she wished to help the team out on their mission. Thea is then informed that Ollie is back in town and she wants to talk to him but Felicity dissuades her. Thea headed back to her Loft and contacted her father, Malcolm Merlyn who informed her that Oliver is hunting down Nyssa so he could kill her and have no rival as Ra's successor. He tried to convince her to not get involved but she protested. He then asked how he can help after she persuaded him to help her. Thea shot Oliver in the wrist with an arrow as he attempted to kill Diggle after a massive fight involving the exchange of Lyla, who Al Sah-him and the League kidnapped for Nyssa broke out. This enraged her half-brother who spared John's life and walked away with Nyssa. Thea then returned back to the Arrowcave with the rest of the team who then admit that they have lost Oliver to Ra's and must now reassemble their efforts without him. Felicity then came over to Thea's place and talked to her about Oliver and them both still loving him. Felicity then told her that they must move on with their lives and informed her about Roy being alive, as well as the fact that they staged his death. Felicity then gave her a paper which had his location and whereabouts and stated that she has an opportunity to start a new life if she wished.
Thea packed and headed to Monument Point to visit Roy. She brought his Arsenal suit, telling him she had her father steal it out of impound. The two share a kiss before having an intercourse. Later, Thea explained what had happened after he left and how Oliver sacrificed his soul for hers. The following day, Thea found herself alone in bed. She went to the auto-shop Roy worked at, only to learn he had quit and left once again. She read the letter Roy had left her, telling her to live the life Oliver sacrificed his soul for, and not live one on the run. Thea then also received Roy's Arsenal suit, the latter stating red always looked better on her.
Thea returned to Starling City in time to face the threat of Ra's al Ghul's bio-weapon attack where she donned Roy's suit and arrived in time to save John Diggle from a league member, who commented on her "threads". Diggle interrogated the assassin for the virus location only to discover he was carrying the toxin in his blood and released it by cutting his own throat. Diggle insisted Thea leave but she assured him that Malcolm had already inoculated her and the two worked together to evacuate as many people as they could to save them from the virus and they took down the fourth assassin before he could release the virus. This bought enough time for Oliver to kill Ra's and Ray to release the vaccine and cure everyone who'd been exposed. Returning to Palmer Technologies Oliver commended the efforts of everyone present and declared his intention to retire, knowing that he couldn't be The Arrow even if he wanted to be and didn't want to be anymore and also acknowledges that the city is in capable hands even without him. At her apartment Malcolm informed Thea that he intended to leave Starling as well which she wasn't phased by, but Malcolm tried to justify that regardless of all he has done he will always love her and will always be there if she needs him. Though she is uninterested in his offer she acknowledges the promise he made to make her stronger and thanks him for it, then tries to convince Oliver not to leave with no luck. Before he leaves Thea asks if he has an idea of a codename for her as she'd thought of "Red Arrow", but Oliver had already told everyone to call her "Speedy". Annoyed but humored Thea bid farewell to Oliver. 
Working with Team Arrow
After Oliver left Thea moved in with Laurel as living in her apartment haunted her of when Ra's almost killed her, but kept the house in her name. Over the next few months Thea, Diggle and Laurel worked to keep the city, re-branded "Star City" in Ray's memory, safe from threats but eventually a new terrorist group the media begun calling "The Ghosts" begun a series of attacks across the city. These begun with robbing banks and jewelry stores but escalated into stealing munitions and technologies, and the "Ghosts" themselves proved all too much a match for Team Arrow's skills.
During one siege of a Kord Industries weapons truck, Speedy and Black Canary moved in to intercept where Speedy fought against a few men. However one of the Ghosts pinned her down but Diggle saved her before Black Canary blew up the truck wheels, but the Ghosts brought backup and escaped with their cargo anyway. At the Arrowcave the team discussed the hijacking and Laurel and Thea agreed that they were outmatched and needed help, Oliver's help. However Diggle was against seeking Oliver's help. Only a day later city leadership was targeted by means of poisonings and assassinations and Thea failed in attempting to save one of them. Interrupting Oliver's dinner with Felicity, The and Laurel arrived at their house and told them of what they were up against and that despite what Diggle thinks, they're outmatched and need The Arrow. Reluctantly Oliver agreed to return home until their new enemies were caught. Eventually they found the Ghosts and observed as their leader addressed his men and killed on of them for failing to kill the vigilantes, simply by touching him. As Team Arrow attacked Speedy engaged one of the Ghosts but became unhinged and repeatedly punched him, almost stabbing him with her sword until Oliver stopped her. As Oliver and Thea searched for the bomb the Ghosts intended to use on the new railway line Oliver addressed her outburst but she tried to assure him she was fine, but Oliver was unconvinced. At the opening of the railway line Speedy use an arrow as a threat to get everyone to leave as Team Arrow worked to stop the Ghosts leader's plan. After succeeding Thea was present as Oliver revealed the leader to be Damien Darhk, Ra's al Ghul's most bitter enemy, but were confused since Damien had already left Star City months ago and Thea and witnessed Oliver in his new Arrow suit broadcast a statement to Star city, declaring his intention to protect it, as "Green Arrow". 
Thea as Speedy helped the team save the Star City Dam from the ghosts. Later, Oliver and Thea were having brunch with an old family friend Jessica Danforth and her daughter Madison Danforth where she told them of her plan to run for Mayor. Oliver and Thea started protecting Jessica from Lonnie Machin, a man hired by Damien Darhk to kill Jessica. While she was torturing a criminal, Oliver sent her away. Oliver later told Thea not to be so aggressive when she's out there. When Oliver was demonstrating what she did, Thea fought back. Thea later told Laurel about her experience in Nanda Parbat. After the team were able to locate Lonnie Machin, Thea went too far and set Lonnie on fire in a rage. Laurel later told Thea they were going to Nanda Parbat to resurrect in sister.
When Laurel and Thea arrived in Nanda Parbat, Malcolm refused to resurrect Sara. Thea told Malcolm about the blood-lust she had recently and asked for his help. Malcalm told her there was a sage on a nearby mountain that could cure her. Later, Thea was awoken by two assassins whom she killed. Malcolm revealed that there was no cure and the only way to stop the blood-lust was to kill. Later Malcolm agreed to use the pit on Sara and Thea witnessed her coming back to life.
When Thea and Laurel came back to Star City she agreed not to tell Oliver about their experience in Nanda Parbat. Thea joined the rest of the team when Oliver announced to them that he intended to run for Mayor and then went down to the teams now lair. When the team needed to attract a team of rogue cops Thea got in touch with her old drug dealer to lure them out. Thea wrote a speech for Olivers announcement and witnessed him give it.
The resurrected Sara escaped and began to attack women that bore striking resemblances to Thea. Sara later attacked Thea at her home, but she managed to fend Sara off and escape, although injured during the altercation. At the hospital, Thea told Oliver that she understood what Sara was going through and confessed what Malcolm had her do to quench her bloodlust and that maybe Sara would be at peace if she killed her. Sara once again attacked Thea in her hospital room and began choking her but was intervened by Laurel and Oliver who were keeping watch outside. After John Constantine, an old friend of Oliver's helped to return Sara's soul to her body, Oliver and Thea made amends as he told her he was in no position to be angry with her for keeping secrets. 
Initially, Thea can be seen as reckless, selfish, impulsive, and immature. She turned to a life of substance abuse and partying to fill the void of losing her father and older brother. However, when Moira tried to be a decent parent for the first time by grounding her for breaking into a store, Thea obeyed the punishment even though she called Moira out at first. She also has a good heart and often tries to do the right thing, and looks up to Oliver. When she meets Roy Harper, a young criminal, she quickly forms a strong romantic attraction, and she is shown to be extremely devoted to him, repeatedly bailing him out of jail. She also showed up to the auction for Unidac Industries to support Walter even though she said she had no intention of going at first. After Roy is saved by the Hood, Thea goes along with him to meet the man who saved his life. This shows that Thea, while young, reckless, and impulsive, has a strong sense of loyalty and camaraderie for those she loves. Thea is also shown to be unpredictable. One example was when she would intentionally show up late to school and sometimes be on time.
After working with Laurel, her partying and drug abusing days came to be exchanged for a more dutiful and emotionally responsible personality. After the quake, Thea became much more responsible, having to fend for herself financially from Moira's imprisonment, and Oliver's self-imposed exile. She eventually became the new owner of Verdant. In Season 2, though Thea was originally opposed to Roy being a vigilante like the Arrow she eventually warmed up to it when Roy saved Sin, though Thea still tried to be involved as much as possible. When Roy is injected with the Mirakuru and becomes more aggressive, Thea begins to feel pushed away as Roy doesn't talk about it with her. When Roy later breaks up with her she becomes extremely depressed. Furthermore when Thea learns that Malcolm Merlyn is her biological father from Slade Wilson, she becomes angry towards Oliver and Moira, for keeping the secret from her, branding them liars and disowning them as family. When Moira is murdered by Slade to protect Thea, right in front of her with her final words to Thea that she loves her, Thea is completely devastated, numb with despair to the point she decides to leave Starling City.
When Malcolm Merlyn appears during the Siege, protecting her from Slade's super-soldiers, saying he was her father, she at first rejected Malcolm, was disgusted by him and even tried to shoot him, (Thea is more like her biological father, then she realizes). However after Thea learned of Roy working with the Arrow, this was the last straw for her and so she went back to Malcolm. Determined not to feel weak or hurt ever again, Thea sought training from Malcolm, to teach her how to defend herself.
After six months' training under Malcolm, Thea has become a much more confident, disciplined, emotionally stronger person and can physically fend for herself as well. Despite Malcolm being a murderer, she has accepted Malcolm as her father and calls him dad. However she also has shown to have become manipulative in lying about not knowing Malcolm, his training her and avoiding any conversations about him with Oliver. Malcolm's harsh training has turned her in a capable fighter as she is able to act quickly and decisively when cornered. This was shown when confronted with the Arrow, she threw glass in his face and kicked him in the groin after which she escaped. Later on, when Thea finally learns of Oliver's identity as the Arrow, she showed great maturity in accepting her half-brother's vigilante identity, she went back to looking up to him and gracefully praised him for all of the lives he'd saved, for all the good he'd done for Starling City, knowing everything he did was to protect her.
However, when she learns from Oliver that Malcolm had drugged and brainwashed her with Vitura and had her murder Sara Lance under his manipulations, Thea is devastated, beyond horrified. She begins to unravel, holding Slade Wilson at gunpoint on Lian Yu, and viciously turns against Malcolm. When faced against the League of Assassins, Thea arranges for them to kidnap Malcolm so he faces justice. When Oliver points out, she will feel guilty for what she did, she tried to brush this off, however, her conscience catches up with her, Thea realizes she tried to have her own father killed while wracked with guilt over Sara and coming to regret every decision she's made since accepting Malcolm. She even attempts suicide by Nyssa's hand. When Oliver returns with Malcolm, Thea, feels remorse for what she did to her father, but covered it up, when she said she would turn him over to the League all over again. She laments she doesn't know what she's doing, who she is anymore.
After being revived by the Lazarus Pit (after she was killed by Ra's al Ghul), her rebirth appeared to have left its mark on her soul. She had a much more actionable persona as well as a dark sense of honor. She feels responsible for her half-brother's defection for his joining the League of Assassins. When Oliver was supposedly brainwashed and had Diggle at sword-point, she shoots an arrow through her half-brother's arm to stop him and threatened him the next would be in his eye. When Roy decides to end their relationship, as well as leaving her his Arsenal suit, she accepts it and is inspired to assume her own mantle joining Team Arrow and operate as a vigilante under the name Speedy.
After six months of being a vigilante, the side effects of the Lazarus Pit's waters started to take affect, Thea has become extremely aggressive and bloodthirsty to the point of being unstable and unpredictable.
- Peak of human physical condition: After 5 months of training, Thea became a strong fighter, that can clash in battle with several opponents. Malcolm Merlyn trained Thea in kenjutsu and martial arts, and after some time, Thea received excellent physical training. During her training and the fight she showed excellent flexibility and coordination.
- Skilled swordswoman: During the five months, Thea went away with Malcolm Merlyn, he has trained her in kenjutsu and other forms of swordfighting. She became so skillful, that she could easily defeat two trainers at once and received praise from Malcolm during their sparring sessions.
- Expert archer: After 5 months of training, Thea became highly skilled in archery. She was able to quickly shoot three arrows to Sara in her chest. She shot an arrow at Oliver's arm with great accuracy.
- Expert knife-thrower: Without watching she was able to throw a letter opener to Malcolm's forehead, which he caught.
- Expert hand-to-hand combatant/Martial artist: Along with highly skilled swordsplay, Thea became a proficient fighter, who can easily beat two trainers. She combines her sword mastery with powerful kicks and punches. When Oliver confronted her (in his guise as The Arrow) she landed a groin kick and then tried to use multiple strikes on him, however, Oliver blocked and dodged her blows, after which she flees the scene. However, she was unable to fight off Chase, an agent of the League of Assassins, and was almost killed, if not for Roy and Malcolm's intervention. Later on, she was able to fend off Slade Wilson alongside Oliver, however, it should be noted that Oliver was seriously injured at the time and if Thea had not pulled a gun on Slade, when she did, she would have been defeated by the latter. Unfortunately, she was no match for Ra's al Ghul, as she was overpowered and almost killed by the latter, this shows that Thea is still not yet at her half-brother and father's level.
- Skilled stick fighter: Thea is skilled in fighting with sticks. Being able to spar with Oliver and impressing him.
- Stealth/Free running/Acrobatics: After 5 months of training, Thea was able to sneak up on Sara who only realized she was there when she called her name. After 5 months of training, Thea was able to escape from Oliver (in his guise as the Arrow) by jumping off her balcony.
- High-level intellect/Expert detective/Great business acumen: Thea is proven to be highly intelligent for her age. She was able to trace the chain from a wallet to Roy Harper, who stole her purse at the time. She can sense when someone is lying or hiding something from her, she figured out that her half-brother and mother were secretly fighting, and she notice that Oliver is keeping a secret about Sara. She took over her half-brother's club Verdant, she became a successful businesswoman and was able to run the club perfectly.
- Toxicology: Thea has displayed a familiarity with poisons, being able to detect disguised cyanide in red wine.
- Tolerance for pain: Thea was also taught by Malcolm to withstand pain by pouring hot liquid over her hand. By the end of her 6 month stay with her when someone accidentally spilled hot coffee on her she didn't even flinch from the pain. When Oliver dislocated her shoulder she merely groaned in pain, showing she was able to tolerate this pain as well.
- Shinai/Bokken: Thea has a wooden sword for training in kenjutsu.
- Katana: Thea has a katana for training in kenjutsu.
- Customized Compound Bow: While killing Sara and shooting Oliver (as Al Sah-Him), she used a bow similar to the one Malcolm uses.
- Jian: Thea has a Chinese straightsword for her training with Malcolm.
- Dark Archer suit: While killing Sara, she wore a dark suit with a hood. The suit seemed to be inspired by the League of Assassins suit her father wears as his persona the Dark Archer.
- Arsenal suit: Thea was given Roy's Arsenal suit to use as her heroic alter-ego, Speedy, to hide her identity from her enemies, when she goes out fighting crime. It is also unknown what materials it is made from; with the exception of Kevlar. It seems to resemble the suit worn by her half-brother. In "This is Your Sword", Roy gave the suit to Thea, claiming that red looked better on her.
- Customized Recurve Bow: While out fighting crime as Speedy, Thea uses a red colored recurve bow.
- Hunting Arrows: While killing Sara, she used hunting arrows similar to that of Malcolm Merlyn and members of the League of Assassins. Later on as her heroic alter-ego as Speedy, she uses red colored arrows similar to Roy's.
- Quiver: While killing Sara, and as Speedy, she wore a dark quiver to carry her arrows with her.
- "All Star Team Up" (mentioned)
Arrow: Season 2.5
- Oliver's nickname for Thea is "Speedy", which she later adopts as her vigilante name; in the DC comics, Speedy is the alias of Green Arrow's sidekicks. The first Speedy was Roy Harper, who in the comics also happened to have a drug problem like Thea. The second Speedy was Mia Dearden, a teenage girl who took on the mantle after Roy switched aliases. Even though Thea was initially thought to be an original character, as seasons progressed, more similarities were shown between her and the second Speedy, like her middle name being Dearden and using the name "Mia" during her time in Corto Maltese. It was eventually confirmed that Thea is indeed a version of Mia Dearden, when she finally joined Team Arrow, under the name Speedy, taking Roy's place, like in the comics.
- Several archery trophies can be seen in her room. This concept recurs when she throws an empty bottle with great accuracy to save Roy from a thug with a gun. She is shown for the first time to actually use a bow and arrows, shooting one of them with great accuracy at Oliver, proving that archery is indeed in her skill set.
- Thea had a brief crush on Tommy and drunkenly tried to kiss him, unaware of her relation to him. She would later realize this after learning Malcolm is her father and feel disgusted by it.
- When Thea found her true parentage she thought "Thea Merlyn" was amusing. Though she is still been referred to as Thea Queen, she has occasionally jokingly refereed to herself with the "Merlyn" surname.
- Thea suggested that her vigilante identity could be "Red Arrow", before being prompted by Oliver to take on the name Speedy. In the comics, Red Arrow was one of Roy Harper's aliases.
- As the daughter of the current Ra's al Ghul it's possible that Thea is also an heir to the demon like Nyssa.