A new fan theory regarding Avengers: Endgame and the effort to defeat Thanos claims Captain America will come face to face with the Red Skull again.
Spoilers for Avengers: Infinity War and Avengers: Endgame follow! Major spoilers!
In Avengers: Infinity War, Captain America: The First Avenger's villain was brought back to the Marvel Cinematic Universe (played by Ross Marquand, this time). Living on Vormir, the Red Skull is burdened with protecting the Soul Stone and explaining to those who seek it that they will have to sacrifice "that which they love" in order obtain it. If Captain America learns of the Soul Stone's location from Nebula or otherwise and time travel becomes a factor, he may end up coming face to face with the man he fought "a lifetime ago."
"So with Avengers: Endgame we're expecting the heroes to go back in time and try to find and or destroy the Infinity Stones, hence the BTS sequences involving them around Battle of NY, and other places," the theory on Reddit begins. "This inevitably gives Rogers the opportunity of living a settled life with Peggy, of returning home, if he's time-travelling (that's what I read out of the compass shown in the trailer).
"Question: So when he finally confronts Red Skull once again on Vormir, in order to get the stone he has to sacrifice something that means the most to him. Do you think this is what he has to give up to get the soul-stone?
"Plus, I think Markus and McFeely and the Russos have thus far pretty much had an interesting dynamic of bringing up real-life political themes and motifs in their films.
With The First Avenger we had Stark's dad experimenting with genetic modification at the time of Nazis;
With Dark World (I'm guessing before the Robert Rodot rewrites it was less Viking-inspired, less about the familial brotherhood and loss, and more surrounding Thor's role as a king) showing us international and personal relations at times of war;
With The Winter Soldier we got Stark's government-surveillance system;
With Civil War we get a glimpse at Stark's concentration camp for super-soldiers (Peter as a child-soldier? Bucky as shell-shocked veteran? Zemo as the civilian striking back?);
With Infinity War we had an entire universe bending to the wills of an genocidal environmentalist tyrant (Stark's whole war fought for no reason other than for resource in a distant land, or fears for a weapon of universal destruction);
And now with Endgame the one political motif connecting the ability to travel through and change history is censorship. Frankly, I don't know how Captain America will feel about that (Stark's alternate realities). But if Cap loses his sense of "being a good man" and allows reality to be altered, then he is allowing history to change, and for someone like Stark or Thanos to do what they feel is right. That would also kill his soul.
"Replacing Red Skull wouldn't be that hard, considering he's used to sacrificing himself for the greater good, no matter what the cost. The only way to defeat Hydra, in the swamps of Lerna, is with fire, and using its blood made Herakles the inventor of the first biochemical weapon in the world: poisoned arrows. It made Herakles become a monster himself."
The details of the theory are making a lot of assumptions regarding Captain America's narrative and other characters coming into play in Avengers: Endgame. However, it doesn't seem entirely unlikely that Captain America has another encounter with his first Marvel Cinematic Universe nemesis when it is all laid out.
Avengers: Endgame hits theaters on April 26, 2019.