If you've been paying attention to all the Easter Eggs the Marvel Cinematic Universe throws at you, then you'll remember one about Tony Stark's left arm. Throughout the MCU films, we've seen his arm bothering Stark a few times, seemingly just for comedic purposes. But it actually might be more than that.

One fan thinks this recurring problem for Iron Man could totally change the outcome in the upcoming film Avengers: Endgame. The idea is that the arm, which pains Stark quite often, could help in stopping Thanos once he slides his arm through the Infinity Gauntlet.

The theory comes from Redditor Dolly_Bakels, who reflects on the final scene in Infinity War where Thanos snaps his fingers. As we see at the end of the film and in the first Endgame trailer, the Gauntlet is damaged and so is Thanos.

“His left arm got all shriveled and looked decayed,” the theorist writes on Reddit. “Now what if Tony’s arm did the same thing, but in the past, where he doesn’t remember it ever happening?”

The fan's theory goes on to assume that time travel will be an essential power in stopping Thanos, and that the Avengers could go back in time and steal the Infinity Stones, to reverse the huge snap that killed half the universe. And the person who puts on the Gauntlet and saves the world? Tony, of course, because all this time his left arm has been in such pain.

The user goes on to explain that Tony has always been seeing Thanos in his head, so there is a legitimate connection of some sort between them.

It would be interesting to see one of these long-running Easter Eggs come full circle in the final Avengers film. If it is true, kudos to the Marvel Studios writers for keeping a secret of that caliber for all these years. Endgame hits theaters on April 26.

[h/t: Inverse]