Marvel Studios' latest TV show debuted one of the franchise's biggest villains, and his arrival leads to the Scarlet Witch's return in a major theory.

For the past four ears, we've had many wild theories as to when and where we'd see the demon lord Mephisto in the MCU.

Marvel's "Ironheart" finally introduces Mephisto (Sacha Baron Cohen) to the MCU. But after years of delays, does it work?