Credit: Marvel Studios In their MCU debut, the Fantastic Four become a Fantastic Five with the arrival of Reed and Sue's son, Franklin Richards. Worries that he might not be "normal" are confirmed in Fantastic Four: First Steps when Galactus recognises that the boy can wield an unlimited energy known as the Power Cosmic (presumably because of the "cosmically compromised DNA" shared by both of his parents).

Based on how First Steps ends, Doomsday will probably open with Doctor Doom kidnapping young Franklin Richards and making a beeline for Earth-616, forcing Reed and his family to pursue. Reed and Vanessa Kirby’s Sue will be desperate to reunite with their son, forming what will surely be one of the key emotional throughlines of the film.

Franklin Richards is an important character for the future of the MCU – and if it’s faithful to the comics, he’ll be incredibly powerful.

Doomsday connects to The Fantastic Four: First Steps? A key mid-credits scene introduces a mysterious presence, hints at a growing multiversal threat, and sets up one character’s deeper interest in Franklin Richards.

How will Marvel Studios reconcile Franklin Richards' abilities with the established power levels and needs of the MCU? Avengers: Doomsday Raises a Big Question About the Fantastic Four - ComicBook.com