Kid Flash has been out of Team Flash for a while, but he'll soon find a home on the Waverider with DC's Legends of Tomorrow, which is sorely lacking a speedster. Legends of Tomorrow executive producer Marc Guggenheim has said that the speedster's appearance is coming in the not-too-distant future and added some details that tease how he ends up joining the team:
Wally is brought to the team by Rip Hunter, of all people, and once he meets them, he realizes this is a good group to stay with.
Wally isn't going to just show up out on his own volition, but instead gets a little help from Rip Hunter, who will be another surprise character returning in Legends of Tomorrow's episode "Here I Go Again." Hunter was last seen in "Return of the Mack" and was arrested by the Time Bureau after Sara turned him over. The midseason finale mentioned Rip had been given a prison sentence, so his upcoming return is a bit surprising. Is it possible Rip used Wally in order to escape the Time Bureau and his prison stint? Is there anything we can really rule out in a show about time travel?
Not too much had previously been released about how and why Wally will join the Legends of Tomorrow team beyond what was originally reported. Early reports had Kid Flash fully joining the team by episode 13. His Rip-assisted arrival in "Here I Go Again" happens a full two episodes before his full induction to the team, so it sounds like it'll take a bit of time for Wally to trust the team as Marc Guggenheim told EW he eventually does.
Wally has been shown in a period of indecision and self-discovery over on The Flash, so it's not exactly surprising he's not immediately going to jump in with the Legends just because he's useful to their team. Of course, it's not like Wally has a lot of options at the moment anyway, as it's been indicated there are no plans to bring him back to The Flash in the near future.
The good news for Flash fans who have been missing Kid Flash is that actor Keiynan Lonsdale has a home on Legends of Tomorrow, although its unknown exactly how long his tenure will last. Ray Palmer actor Brandon Routh remarked Lonsdale would be with the series "a short time," although he gave that quote prior to the revelation that Lonsdale was made a series regular on Legends of Tomorrow. However long Lonsdale is on the series, it's certainly better than nothing. Fans of the Arrow-verse shows have seen very little of his character as of late.