Robert Downey Jr.'s latest behind-the-scene tease for Avengers: Doomsday suggests a fan-favorite superhero team could join the MCU.

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).

First Steps was just about reboots and retro vibes, think again. With their First Family, Marvel is cracking open a cosmic door to something far bigger.