Fantastic Four: First Steps Trailer

A new theory perfectly explains the alternate universe setting of The Fantastic Four: First Steps by introducing a powerful new character to the MCU. Shortly after the cast of The Fantastic Four: First Steps was confirmed on Valentine's Day, theories began to emerge suggesting that the movie could be set in a retro-futuristic, 1960s-themed alternate reality of the MCU. This has since been confirmed by Marvel Studios and director Matt Shakman, but this has spurred more speculation about the story details of the Fantastic Four's much anticipated MCU debut.

Popular theories have suggested that the Fantastic Four originated in Earth-616 and became trapped in another universe after a failed experiment, or come from across the multiverse and will move to the MCU's main continuity upon Galactus' destruction of their world. However, a new theory posed by Reddit user Armchair Of Heresy posits that a rumored new character in The Fantastic Four: First Steps may have created the movie's alternate universe himself. This is a very exciting prospect that could set up several future MCU projects.