Red Skull is Steve Rogers’ true nemesis as the HYDRA leader is a twisted reflection of Captain America. Both Johann Schmidt and Rogers took Dr. Erskine’s Super Soldier Serum, but while the latter became a paragon of strength and courage, the former was hideously deformed, hence the nickname given to him by Adolf Hitler. But why exactly did this happen to the villain?
Well, Erskine tells Steve that it’s because the serum amplifies the properties already within the person who takes it (“good becomes great, bad becomes… worse”). However, this doesn’t really explain the physical transformation that Schmidt went through. Reddit user u/rafael-a has now shared their thoughts on the science behind Red Skull’s origins, though, to the r/FanTheories subreddit, and what they put forward is pretty convincing.
They suggest that the shot of penicillin Erskine gives Rogers before his treatment was the all-important part of the process that Schmidt overlooked, saying:
“In the scene of the transformation of skinny Steve Rogers into big buff Captain America there is a small joke where Erskine injects him [with] penicillin beforehand. The penicillin shot was much more important than it seems, because [the] human body is full of bacteria, and the Super Serum would enhance microbes as well. Therefore they should be killed beforehand.”
It’s possible, then, that the bacteria in Schmidt was amplified in strength just as he was, causing it to eat at his face and presumably, his body.
“In the movie, it is shown that Johann ‘Red Skull’ Schmidt injected the serum by himself. It worked but it also enhanced the bacteria [that] grow in such a way that they destroyed the skin of his face (and maybe [his] entire body). And it would have killed him if he wasn’t enhanced as well. So his body is in a constant battle against super microbes and that messed up his face.”
Despite his terrible disfigurement, Red Skull has actually had an incredibly long life. He was thought to be killed by the Tesseract in 1945, but in fact, he was pressed into the service of the Infinity Stones, tasked with guarding over the Soul Stone on Vormir for decades. It’s been confirmed that, following Thanos claiming the gem, Schmidt now has his freedom back, but will he return to Earth to get revenge on the new Captain America, Sam Wilson? We’ll have to wait and see.