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).
It's this same energy that powers the Devourer of Worlds, as well as his herald, the Silver Surfer, which makes Franklin the perfect person to become his successor and relieve Galactus of the insatiable hunger that's consumed him for millennia. It also makes Franklin a key player in the upcoming film Avengers: Doomsday, one who could very well hold the key to defeating Doctor Doom when no one else can. Full spoilers for the events of Fantastic Four: First Steps follow.
