In Marvel Comics, Franklin Richards is an immensely powerful mutant who can alter reality itself. This comes from the cosmic ray-mutated genes he inherited from his parents. "The Fantastic Four: First Steps" depicts Franklin in the same way; his powerful potential is the driving force of the movie.

A good chunk of Doomsday could focus on a clash between Avengers and X-Men with RDJ’s Doom cackling in the background, with a kidnapped Franklin by his side. The premise certainly gives the Fantastic Four a reason to breach their multiversal walls and zip over to 616 to meet the New Avengers.

First Steps' includes two post-credits scenes. Here's how that big reveal sets up what's coming in Phase 6 of the MCU.