A new fan theory says the first Iron Man film has a clue as to why Tony Stark was able to wield the Infinity Stones in Avengers: Endgame.

The philosophy behind Mewtwo’s creation was to make the world’s strongest Pokémon. Little did the scientists know how right they would be. Mewtwo far surpassed their expectations, unwilling to be controlled by any corrupt official. He destroyed the laboratory that built him before traveling on his own and going into hiding. Several times, Mewtwo has come out to cause strife in the real world, but he mostly keeps to himself.