DC Universe "Lost Year"
After the events of Infinite Crisis, the DC Universe leaped over one entire year of continuity. One of the teams that suffered many changes because of Infinite Crisis was the Teen Titans. Having had the death of Superboy (Connor Kent), the leaving of Speedy, Wonder Girl, Bart Allen and Robin, as well as having Cyborg in a coma, the team was in poor shape.
Beast Boy and Raven tried to keep the team together, using a membership drive to have both new members and to keep members of Lex Luthor's "Everyman Project" close. During this missing year dozens of young heroes joined the ranks of the Teen Titans just to leave shortly after.
Talon was one of the many heroes that joined the Teen Titans during this missing year, along with former Teen Titan Duela Dent. However, both of them ended up departing the team.
At the start of Countdown to Final Crisis, Duela Dent was murdered at the hands of one of the 52 Monitors because she was considered a multiversal anomaly. Jason Todd, along with Donna Troy and another Monitor began a search to find Ray Palmer (The Atom) because he was the only person that could prevent the so-called "Great disaster". During their search for Ray Palmer the team would be joined Ryan Choi and Kyle Rayner.
After Choi was brought back to their Earth, the Challengers from Beyond crossed the DC Multiverse in search of Ray Palmer. One of the Earths they stumbled across was Earth-3. It was here that they were confronted by the Crime Society of America, a villainous version of the Justice Society of America and met The Jokester, who was a heroic version of the Joker.
During Countdown Presents: The Search For Ray Palmer: Crime Society #1, a one-shot based on the search of Ray Palmer, the Jokester origin's was explained. It revealed that Duela Dent was actually the daughter of the Jokester and that Talon was the sidekick of Owlman.
Owlman and Talon terrorized Gotham city and had various encounters with The Jokester (who had actually killed Talon's predecessor, mirroring The Joker's murder of Jason Todd) and his allies. However, Talon fell in love with Duela Dent, The Jokester's daughter and after revealing their secret love, both of the teens were disowned by their families.
Duela and Talon then travelled to New Earth, where they both joined the Teen Titans during the Lost Year following the Infinite Crisis.
Talon's identity is a secret.
The New 52
Talon was only mentioned in Justice League #23.4 by Owlman while talking to The Outsider. Owlman briefly mentions that he murdered Talon's parents and after he broke the news, he ran away to go after the Joker where he is killed and dismembered. When Owlman catches up to the Joker, he is given six boxes, each containing a different limb.