How Franklin Richards, the power cosmic and Doctor Doom's appearance in "The Fantastic Four: First Steps" credit scene affects "Avengers: Doomsday."

Robert Downey Jr's Doctor Doom's motivation for potentially going after Marvel's first family might boil down to Franklin Richards' powers.

In Marvel Comics, Doom’s fixation on Franklin is legendary. He views the boy’s near-limitless powers as the key to creating and ruling Battleworld, a twisted reality of his own making as seen in Secret Wars.