|Occupation|| Owner of Verdant|
Student (formerly; graduated)
Intern at CNRI (under court order; formerly)
|Family|| Malcolm Merlyn (father)|
Moira Queen (mother; deceased)
Oliver Queen (maternal half-brother)
Robert Queen (step-father; deceased)
Tommy Merlyn (paternal half-brother; deceased)
Walter Steele (step-father; formerly)
- "Thea Queen was also weak and no matter what it takes I will be strong."
- —Thea Queen 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 maternal younger half-sister of Oliver Queen, and the paternal younger half-sister of the late Tommy Merlyn. Thea is also the girlfriend of Roy Harper.
Thea is the daughter of Moira Queen and Malcolm Merlyn, 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 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.
In "Pilot", 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.
In "Lone Gunmen", Thea is brought home by the police after a night of drunken partying that led to breaking and entering a shop. Despite being grounded, she parties at the nightclub Poison, where she bumps into Oliver, and the two have an argument. Thea discloses to Oliver that Laurel and Tommy have been sleeping together in his absence and stumbles off. Thea tones down her wild behavior towards the end of the episode, having a mother-daughter moment with Moira, and appearing at the Unidac auction.
In "An Innocent Man", Thea bonds with Oliver while they discuss Laurel, and how Oliver can get back into her "good-books" again.
In "Damaged", Thea and her family are worried for Oliver after multiple charges are brought against him by Sergeant Quentin. Thea shows how much her brother's absence has affected her when she tells Oliver that "she can't lose him again". Oliver reassures her at the end that she won't.
In "Legacies", Thea is shown to have a crush on Tommy, after he comes asking her for romantic advice. Things, however, get very awkward when she realizes he meant Laurel instead of her. Thea ends up getting drunk at the CNRI benefit, and Tommy takes her home.
In "Muse of Fire", 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 is with Moira at the hospital and later seen telling Oliver off for leaving Moira and going after the shooter. Thea stays in that night with Moira after Oliver tells her he has a business meeting, talking to Moira how she wishes that Oliver wouldn't lie and tell them what's wrong. Thea then speaks to Oliver, saying that he shouldn't keep what happened on the island a secret, and that he should tell someone about what happened.
In "Vendetta", Thea is seen asking Walter for a lift to school, commenting that they could just buy her a convertible to save them the trouble.
In "Year's End", Oliver is talking to Thea about why there are no Christmas decorations up, and she explains how they hadn't really celebrated Christmas since Oliver and Robert had disappeared. Thea is later seen at Big Belly Burger with Oliver, discussing why there is no Christmas Party when Thea's friend Shane shows up. Oliver later walks in on Thea and Shane at the Christmas Party and catches them making out with some clothes off. Oliver tells the boy, "Hit the road." She later admits she was being a "bitch", when Oliver is injured, at the hospital.
In "Burned", Thea is seen with Oliver, going through movies to watch, telling him how Moira is acting the same way now as when Robert and Oliver disappeared. Thea is later seen trying to convince her mother to leave her room and go out with her. She later comments on why Oliver is smiling, saying that his club burnt down.
In "Trust but Verify", Thea believes that her mother is having an affair with Malcolm Merlyn. On her 18th birthday, she gets into a car crash and is taken to the hospital. At the end of the episode, it is revealed Thea crashed because of a drug, called vertigo, was in her system. Because she was driving under the influence of drugs, she was arrested.
In "Vertigo", 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 is 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 talks 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 refuses the deal just to spite her mother, who she thinks is cheating on Walter and cheated on her father, as well. Oliver decides to convince her otherwise by revealing that their father cheated on their mother. Thea forgives her mother, when she overhears her mother confirm what Oliver revealed to her about their father. She then decides to take Laurel's offer and work with her.
In "Betrayal", Thea is at CNRI with Laurel, complaining about how long she has left to work, hearing about how Cyrus Vanch is being released. She sees herself as a 'court-ordered slave', and asks "how this [her 500 hours of community service] is not cruel and unusual punishment".
In "The Odyssey", Thea is seen at the end of the episode, stating that she's been trying to ring Oliver all night as Moira was attacked by the vigilante.
In "Dodger", Her purse gets stolen while she is out with Laurel. The thief who stole it was Roy Harper. Thea takes pity on him and drops the charges. She then tracks him down at his home in The Glades.
In "The Huntress Returns", When Thea goes to see Roy again he brushes her off, but saves Thea from some thugs. In doing so, he gets stabbed, and Thea has to take him to the hospital where he has to get a shot, which Roy is scared of. She tells him to take his mind off of it, to he responds by he doesn't like sharp things. When the doctor is gives Roy the shot, she kisses Roy to distract him from it.
In "Salvation", She and Roy are in a romantic relationship, and Thea sees Roy being kidnapped by The Savior. When he is interrogated, she is watching and Oliver goes up to her. She is crying, and Oliver promises that Roy won't die.
In "Darkness on the Edge of Town", Thea continues to help Roy find the Arrow but Oliver tells Roy not to and Thea agrees with him but Roy doesn't, leading to them briefly splitting.
In "Sacrifice", after hearing Moira's revelations, she goes to the Glades to help save Roy. She throws an empty glass bottle at a gang member who was about to shoot Roy. When Roy sees people on a bus trapped, Thea tells Roy not to help because the device could go off any second. Roy tells her he can't leave anyone behind and tells Thea to get out of the Glades.
In "City of Heroes", 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 Arrow'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 Arrow, managed to save her. Later Thea visited Moira in prison telling her about her near death experience, and reconciled with her mother.
In "Identity", After Roy was arrested during his self attempt to fend off the hijackers, Thea gave Roy a ultimatum, which he later telling her that he chooses her and done being the hero, unknown to her lying about stopping trying to be a hero.
In "Broken Dolls", During Moira's trial both Oliver and Thea were stunned, when the A.D.A Adam Donner wants to seek the death penalty for Moira, Oliver later encourages Thea that they both gonna help their mother to fight for her life. Later they both watch the news of the Lances kidnapping.
In "Crucible", During the events of cash for guns Thea meets Sin. When the events were crashed by The Mayor both Roy and Thea evaded getting shot by hiding behind a car, when Sin get shots Thea went to get help for her. Later both Roy and Thea stayed in the hospital by Sin's side, when She comments to Thea that she is dating a moron and Thea agrees and Sin admits to Roy that she likes Thea.
In "League of Assassins", Thea is 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.
In "Keep Your Enemies Closer", 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.
In "State v. Queen", 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.
In "The Scientist", 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.
In "Three Ghosts", 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.
In "Blast Radius", 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.
In "Blind Spot", 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",
In "Birds of Prey", 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.
In "Deathstroke", Thea is 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 and Oliver.
In "The Man Under the Hood", 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.
In "Seeing Red", 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.
In "City of Blood", Thea attends her mother's funeral and is visibly upset that Oliver was unable to attend. Isabel later comes to her club to reclaim it, as it was built upon property owned by Queens Consolidated, then she tells Oliver that she doesn't want to give Isabel the satisfaction of kicking her out of her own home and that she needs a change of scenery. Oliver agrees and lets her go. Thea packs her things in a backpack, takes one more look around her home, ignoring a call from Walter, she leaves. Just as she is about to board the train, one of Slade's agents attacks the station.
In "Streets of Fire", Thea attempts to flee but is saved by her biological father, Malcolm Merlyn. Malcolm tries to talk to her but Thea runs off, wanting nothing to do with him. They are both attacked, but Malcolm is able to subdue the mirakuru soldier. Thea grabs a gun off the ground near a dead cop and shoots Malcolm as he tries to reason with her,
In "Unthinkable", Malcolm is shown to still be alive and reiterates that he needs Thea by his side, going as far as to compare her qualities to everything his own son lacked. Thea leaves and reunites herself with Roy. Deciding to help everyone else, Roy tells her to stay at his house and pack her things. Upon discovering that Roy is secretly the Arrow's sidekick, which he kept from her all along, she ultimately decides to start her life over. Leaving a goodbye note to Roy, Thea decides to go with her father and leaves Starling City and her family behind, with no intentions of coming back.
Training with Malcolm Merlyn and returning to Starling City
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 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.
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 Malcom 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 when 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 discovers that Malcolm released Slade from a A.R.G.U.S. from a 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 manage 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. as 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.
In Nanda Parbat, Thea along with Oliver continues to train with Malcolm. She still struggles 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 contacts the league and makes a deal to hand her father over to the league. Nyssa and the league show 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.
In The Offer, Nyssa refuses to believe Thea's confession, but Thea informs 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 informs her that there would be no justice in killing her and that this will 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 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 surprises her. He then orders her to kill him but she declines. She then talks to Oliver about Malcolm as well as her mom 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.
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 she 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. 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.
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. However after Thea learned of Roy working with The Arrow, this was the last straw for her and so she went back to him. 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 seemed to have 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 maturity in accepting her 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 Thea learns from Oliver that Malcolm had drugged 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, she guiltily informs Laurel 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 returns with Malcolm, Thea realizes she tried to her own father killed while still feeling guilty over Sara's death and coming to regret every decision she's made since accepting Malcolm. She even attempts suicide by Nyssa's hand. She laments she doesn't know what she's doing, who she is anymore.
- 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 was also 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 nearly got killed, if not for Roy and Malcolm's intervention.
- Skilled stickfighter: Thea is skilled in fighting with sticks. Being able to spar with Oliver and impressing him.
- Free running/Acrobatics/Stealth: 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.
- 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 tolerant to 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, she used a bow similar to the one Malcolm uses.
- Jian: Thea has a Chinese straightsword for her training with Malcolm.
- Dark Archer Costume: While killing Sara, she wore a dark costume with a hood. The costume seemed to be inspired by the League of Assassins Costume her father wears as his persona the Dark Archer.
- Hunting Arrows: While killing Sara, she used hunting arrows similar to that of Malcolm Merlyn and members of the League of Assassins.
- Quiver: While killing Sara, she wore a dark quiver to carry her arrows with her.
- Oliver's nickname for Thea is Speedy; in the DC comics, Speedy is the alias of Green Arrow's sidekicks.
- Thea is initially thought to be not specifically based on any character from the DC comics; however, as seasons progress, more similarities are shown between her and the second Speedy.
- Andrew Kreisberg posted an image of Thea's hospital bracelet in a then-upcoming episode of Arrow on Twitter. The bracelet is labeled "DOB: 21-01-1995," revealing her birthday.
- An archery trophy can be seen in her room in "Pilot". This concept recurs in "Sacrifice" when she throws an empty bottle with great accuracy to save Roy from a thug with a gun.
- When Thea was attending school, she would often like to intentionally be late and sometimes be on time "to spice things up."
- Thea, until "Deathstroke", was the only character who was in no way involved in any of the secrets of the series.
- 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. Since she left with Malcolm Merlyn himself many have speculated that she has renamed herself in the name of the Merlyn family. Though after her return to Starling City, she is still been referred to as Thea Queen.