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

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.

As Fantastic Four: First Steps heads towards its final act, the group is torn between two impossible choices: sacrifice all of Earth to Galactus, or Reed and Sue must give up their child Franklin, who contains the Power Cosmic and enough energy to satiate Galactus' hunger.