
Peacemaker (John Cena) and Rick Flag Jr.'s (Joel Kinnaman) rivalry in the DCU came to a fateful head, and it will have consequences in Season 2 of Peacemaker. Flag was the leader of Task Force X in both Suicide Squad and James Gunn's The Suicide Squad, the latter of which was Peacemaker's introduction into the DCU. Flag and Peacemaker were quickly at odds with each other, and their dislike grew as the film continued, ultimately culminating in Flag's death.
Despite being released during the old DCEU, elements of The Suicide Squad (directed by James Gunn) have been incorporated into Gunn and Peter Safran's new DCU. This has led to some of the film's events becoming canon and forming the basis of Peacemaker's spin-off series on HBO Max.
Why Peacemaker Killed Rick Flag In the DCU

Rick Flag, a military veteran and the expert leader of Amanda Waller's Task Force X, found his match in Peacemaker, the helmet-wearing pacifist who was violently committed to his cause. The duo shared physical strength and abilities, and were both expert marksmen and combatants.
Throughout their time in The Suicide Squad, Peacemaker and Flag bickered, often disagreeing on how to tackle situations, such as Flag's decision to divert their mission to rescue Harley Quinn (Margot Robbie).
The two reached an impasse when Flag learned the truth that Amanda Waller was hiding from him: that Task Force X was sent to cover up the government's involvement with Project Starro. Flag stole a hard drive that would reveal to the world that the US government was conducting experiments on Starro and intended to turn it into a weapon.
Peacemaker was then forced to stop Flag from exposing this information on orders from Waller. Peacemaker tried to dissuade Flag, making it clear he did not want to have to kill him. After a brutal fistfight, in which Flag almost had the upper hand, Peacemaker ended things by stabbing Flag through the heart with a shard of debris.
How Peacemaker's Rick Flag Decision Will Impact 'Peacemaker' Season 2

Peacemaker was the only member of Task Force X who remained loyal to Waller in The Suicide Squad and ended up fighting against Bloodsport (Idris Elba) and being mortally wounded for his trouble. He continued to work with ARGUS in Peacemaker Season 1, forming his own team to undertake their missions.
In Season 2, Peacemaker's decision to kill Rick Flag will come back to haunt him, as the new director of ARGUS is introduced, Rick Flag Sr. (Frank Grillo). Flag Sr. has been seen twice in the new DCU before, in Creature Commandos and Superman, but Peacemaker Season 2 finally brings the US General face-to-face with his son's killer.
Flag Sr. will make his debut in the coming weeks on Peacemaker Season 2, and the confrontation is already set up to be explosive. Teasers for the HBO show have hinted that Flag Sr. intends to find Peacemaker for using his father's pocket dimension. Furthermore, Flag Sr. still has a vendetta against the antihero, claiming, "I need to find Peacemaker. He killed my son."
Clips have hinted at Flag Jr.'s legacy being a part of Peacemaker Season 2, with a shot of the character's funeral included in the teaser. The grief for his son will no doubt be a large part of Flag Sr.'s role in Peacemaker Season 2, which will culminate in a violent fight at some point between him and the titular character, as hinted at in the trailer. "My son is a better man than you could ever dream of being," Flag Sr. says, before beating Peacemaker up. The military veteran clearly wants revenge for his son's death, which spells bad news for Peacemaker.
The trailers hint at Peacemaker trying to reconcile his past mistakes in the new season, which likely includes atoning for his part in Flag's death. However, at one point, the hero states, "I'm not sure redemption is possible here," suggesting that The Suicide Squad event is one of the big regrets the character struggles with throughout the new season.
The second season of Peacemaker debuted its first episode on HBO Max on August 21, heralding the return of Cena as the helmet-wearing antihero Christopher Smith, and his colleagues Vigilante (Freddie Stroma), Adebayo (Danielle Brooks), and Harcourt (Jennifer Holland). Gunn created and directed the series, which has several connections to his recent DC Studios film Superman.