Of all the original Avengers left standing at the end of Avengers: Endgame, the one with the least clear path forward was Bruce Banner/Hulk.
Endgame did set up some threads for Hulk to follow – he finally managed to reconcile his Banner and Hulk personas, and even survived wielding the Infinity Gauntlet (even though it cost him an arm). And it’s that last bit that may provide a clue to one possible cinematic future for the Hulk.
When Hulk argues for himself to be the one wield the Infinity Gauntlet to counter Thanos’ snap, he says the energy emitted by the Infinity Stones is “mostly Gamma,” meaning Hulk is not only able to withstand it – he can potentially absorb some of that Gamma radiation.
And now that the Infinity Stones are gone – snapped away by Thanos himself – that Infinity Stone energy is out there somewhere (we’ve made a case for one of the possible effects already). So what if Hulk, who absorbs and channels Gamma radiation, and who has even used the Gauntlet himself, has some longer-term side effects that could end up pushing him into a dark place - one presaged in comic books?
In comic books, something like that has already happened in Peter David and George Perez's 1992 limited series Incredible Hulk: Future Imperfect.
In that story set 100 years in the future, Hulk absorbs massive levels of radiation after a nuclear conflagration decimates the Earth. And though it gives him a huge power increase, it also drives him mad – leading him to become the Maestro, a fully-intelligent, insanely strong, but evil version of the Hulk. In Future Imperfect, Maestro took on the entire assembled Avengers, even killing several. And his appearances didn’t stop there.
In 2002, then-Captain Marvel Genis-Vell and Spider-Man 2099 were traveling through time and ran across Maestro. They survived, but years later Spider-Man 2099 attempted to return to his own time - ending up in a new, alternate future ruled by Maestro. Maestro imprisoned Miguel O'Hara, using his time travel device in a failed attempt to conquer the Marvel Universe in the present day.
In 2015, Future Imperfect was revived as a component of Secret Wars' Battleworld. And most recently, Maestro was a primary character and antagonist in Marvel’s Contest of Champions game and tie-in comic book, where he assembled warriors to compete from around the multiverse (a concept the MCU seems to be flirting with).
Could Hulk have absorbed too much Infinity-Gamma energy and and be on the path to becoming the Maestro? With his arm withered, would Bruce Banner (who has never taken failure lightly) attempt dangerous experiments to restore or boost himself, as he did when he mastered the Hulk after being beaten by Thanos in Avengers: Infinity War?
Such a story could even incorporate a return for any of Hulk’s previous MCU supporting characters, especially Tim Blake Nelson’s Sam Sterns, who was on his way to become the Leader when he was last seen in 2009’s The Incredible Hulk.
Fans of Mark Ruffalo’s affable “I’m just doing my best” take on Bruce Banner may balk at the idea of ol’ Jade Jaws breaking bad – but that’s part of what makes it such a compelling possibility for how to send off a fan-favorite superhero. And, if the next iteration of the Avengers needs a one-off mega-villain (a la Ultron), Maestro has more than enough firepower to challenge Earth’s Mightiest Heroes both physically and emotionally.
Avengers: World War Hulk, anyone?