Actor Colton Haynes is returning to Arrow for season 7 - but jut how he's being written back into the series is a mystery. Last we saw Haynes' character, Roy Harper, he had faked his own death after trying to take legal blame for being the Green Arrow. Roy then joined Thea Queen and Nyssa al Ghul on a quest to travel the world and eliminate the rest of the League of Assassins' Lazarus Pits.
The Arrowverse has created several routes for actors to reprise their characters in different forms - whether pulling characters from the past and/or future, or introducing alternate versions from other dimensions. However, in an interview with EW, Marc Guggenheim assured Arrow fans that no such trickery will be needed to explain Roy's return:
“I can tell you it’s absolutely our Earth’s Roy. Colton is coming back as our one Roy Harper. We have a cool plan for Roy — now I should really get into the habit of saying the writers have a cool plan for Roy — but I think it’s premature to talk about that."
Arrow season 6 concluded with Oliver Queen being locked in Super Max prison for his activity as Green Arrow, while gangster Ricardo Diaz survived to terrorize Star City another day. The cast and crew have already teased what that threat looks like for Team Arrow while Oliver is locked up, so it's not hard to imagine them needed all the help they can get. Since Roy has spent some time on the run, hiding his identity from public scrutiny and law enforcement, so he would be a natural go-to option to help protect the members of Team Arrow (Felicity and William especially). Not only could Roy help hide Felicity and William, he could also work with Felicity in her Overwatch capacity, to try and bring Diaz down, and/or work on getting Oliver out of Super Max. An even more interesting scenario might be having Roy be a surprise inmate at the Super Max, given his confessed history of vigilante activities. If he got picked up by the FBI or other law enforcement during his Lazarus Pit quest, it'd be only natural he'd end up there.
Whatever the case, fans will be ecstatic to see Haynes back as Roy - in whatever capacity it may be. The actor left the show in season 3, citing a lot of mental and emotional risk factors as the reason. He continued to be wary of the spotlight, as news of his sexuality as a gay man leaked into the press, Since that time, Haynes has matured, he got married (and is now getting divorced), and has seen an outpouring of fan love and support. Hopefully he's in the right place to take up his place in Arrow once again - and all the fandom that comes with it.
Arrow season 7 premieres this fall on The CW.