Warning: Contains SPOILERS for The Suicide Squad.
John Cena will return in HBO Max's Peacemaker spinoff show, and The Suicide Squad's story and post-credits scene sets up how and why he'll be back. Among the many new additions to The Suicide Squad's cast of characters is Peacemaker, real name Christopher Smith, and he's one of the most memorable members among the new Task Force X. Essentially an extreme Captain America, he'll do whatever it takes in order to achieve his warped form of peace.
In The Suicide Squad, that extends to betraying his team and leader Rick Flag (Joel Kinnaman), and almost killing Cleo Cazo, aka Ratcatcher 2 (Daniela Melchior). In return for his efforts, he gets shot by Robert DuBois, aka Bloodsport (Idris Elba), which seemingly kills him. Except, of course, it was already confirmed long ago that Cena was starring in a Peacemaker TV show. Once again written and directed by Gunn, Peacemaker was filmed during the pandemic and is expected to release on HBO Max in 2022. While it theoretically could have been (and may still be, in part) a prequel, it does mean his "death" isn't permanent.
In The Suicide Squad's post-credits scene, it's revealed that Peacemaker is miraculously still alive, despite having been shot in the throat (via a bullet through a bullet) and bleeding out. Quite how he survived is something the spinoff may well explain: while he's a highly trained fighting machine and killer, he does not possess any superpowers that would suggest he could live from such a wound, let alone return to his former glory. It may be that he ends up being enhanced in some way, essentially turning him into a super soldier (hammering home those Captain America comparisons). More pertinent, though, is that he's still needed to help save the world, with A.R.G.U.S. recruiting him once again to deal with a new threat, who will presumably be the main villain of Peacemaker.
The post-credits means that Peacemaker will almost certainly be leading his own team - whether that's a new iteration of Task Force X, or more likely something a bit different and smaller since it's not a Suicide Squad movie - and that's something the film also sets up. It sees his views and style clash with Bloodsport, and him kill Flag in order to do what was necessary; or in other words, to be the leader Flag refused to be. That should very much factor into the Peacemaker show, with Smith perhaps heading up a team of other crimefighters who'll do whatever it takes. Freddie Stroma and Nhut Le have been cast as Vigilante and Judomaster, respectively, and could be part of whatever team Peacemaker leads for A.R.G.U.S. Likewise, Waller's assistants who collect him from the hospital - Steve Agee's John Economos and Jennifer Holland's Emilia Harcourt - will be back for Peacemaker too, with The Suicide Squad's ending setting them up as being responsible for Peacemaker now, rather than Waller.
Peacemaker is expected to dive into the character's backstory, and while there's definitely a tease for what's to come in the future, The Suicide Squad does also leave his past very much open as well. Besides the character traits that define him in terms of his fighting ability, there's little revealed about Peacemaker's history to fully explain what happened to turn him into this person. With The Suicide Squad purposefully focusing much more on the character's present and setting up what's next for him, then it does also mean the show can span different timelines or utilize flasbacks in order to show Peacemaker's origins as well.
