@bunny234567 I LOWKEY JUST COPIED AND PASTED FROM A SITE

what

This theory elaborates on the possibility that Chris Evans will follow RDJ's lead and return as a villainous Steve Rogers in a dark subversion of their MCU legacies in Avengers: Doomsday. In the comics "Avengers: Standoff!" and "Secret Empire," Steve Rogers' memory is manipulated by the Red Skull and the sentient Cosmic Cube (which became the Tesseract in the MCU), Kobic, into recalling himself to be a Hydra sleeper agent, culminating in him adopting the Hydra Supreme mantle and attempting to bring about Hydra's global domination.

I like the idea that Red Skull has been sitting on this plan for all the years he has spent on Vormir. He is already intimately connected with at least one of the Infinity Stones, and a little narrative magic is all it takes for him to imbue these new memories in Steve when they are reacquainted during Steve's mission to return the Infinity Stones. It would additionally deliver the elaboration for which fans have been clamoring about Steve's mission and his activities since Avengers: Endgame.