|Family||Unnamed (father; deceased)|
Unnamed (mother; deceased)
On May 10, 2008, Cindy went to a sports game with her father. He took a photo of her and kept it in his wallet. The following year, Cindy's father was shot down while flying a plane over Lian Yu, and soon died from wounds sustained in the crash. However, before he died he asked Sara to find and look after Cindy. At some point Cindy choose the nickname "Sin".
After the Undertaking, Sin was attacked by a group of men attempting to rape her, but luckily she was saved by The Canary.
Roy Harper was pointed in her direction when looking for The Canary. When asked about her, she led him to The Canary's hideout and knocked him out. When he woke, she looked on as he was questioned by The Canary, but she let him go when The Canary told her he was harmless.
Sometime later, Sin shared breakfast with Sara Lance, the alter ego of The Canary, and they both talked about their families. She later encountered Roy again and met Thea Queen, and she mentioned to him how Thea didn't know about him being The Arrow's sidekick. When The Mayor attacked the event they were at, Sin was wounded and was saved by Roy and Thea. As she was recuperating at a hospital, she was looked over by Roy and Thea. She woke up later and told Roy that, because he saved her, she would keep his secret. She commented on how Roy was an idiot, and Thea whole-heartedly agreed, leading to Sin admitting she had begun to like Thea.
Not long after this, Sin told Roy and Thea of her friend, Max Stanton, who had gone missing for a week. She asked Roy if he knew someone that could help, but Thea commented that Roy could, and the three of them joined in on a search.
In "Three Ghosts",
In "Blind Spot",
In "Time of Death", Sin attended a welcome home party for Sara Lance, and when she was introduced to her (the others not knowing of their friendship), Sin was quick to hug her, arousing suspicion among the others. Later when Sara had reconciled with her family, she reassured Sin that despite her having her big sister back, she would always consider Sin a little sister.
- In the comics, Sin is much younger; she is a child who was destined to become the next Lady Shiva, but she was adopted by Dinah Lance and Oliver Queen.