I've been thinking about it a lot over the past few days - in particular, I've been stewing over the fact that two characters in particular could have had a canon-compatible happy ending, but didn't.
This post contains HUGE spoilers for Endgame, so if you're avoiding those, please bookmark this post and come back to it after you've watched the movie.
Are you spoiler-proofed? OK. Here we go.
The heroic sacrifices of Tony and Natasha were poignant and necessary to the Avengers' victory, but for the two of them to STAY dead was not.
If anything, their continued state of deadness was LESS probable than their resurrection, because if I thought of a canon-compatible way to save them before the movie even ended, Bruce Banner can, too.
If you're still sad about their deaths, and you'd rather mentally live in a world where they're still alive, here's a short fanfic I recently wrote, in which Bruce did what he SHOULD have done in the movie.
If you aren't interested in the fanfic, and just want the fan theory:
As long as the Infinity Stones are present and intact, they maintain a stable flow of time, and removing a person or item from the past doesn't seem to change how that person/thing affected the timeline after they were removed.
Because of this, through the power of quantum time travel, Past Gamora was able to reenter the timeline after the point where she was sacrificed to the Soul Stone, without causing her to be absent in the years between her removal from the timeline and her return in Endgame.
Thanos, too, was retrieved from the past without disrupting the sequence of events in the primary timeline. Even after the Stones were destroyed, the disappearance of his past self didn't stop him from having been present in his retirement home when the Avengers arrived.
That being the case, if versions of Tony and Natasha were removed from the timeline before the Stones were destroyed and brought to the present, their actions after their removal would have been preserved.
Nat would still get the Soul Stone for Clint, and Tony would still destroy Thanos' army, but both characters would still be alive.
There would still be a cost. Heroic sacrifices don't come for free.
These past versions of the fallen heroes would be missing at least five years' worth of memories - which, in Tony's case, includes ALL his memories of his daughter. He would have to rebuild his relationship with her from scratch.
They would both forget all the time they'd spent bonding with people after the Decimation, the new friendships Nat had formed, and the years Tony and Pepper had spent as husband and wife.
But there would still be hope. They'd still be alive.
And all the people who loved them, in their universe and ours... all the trauma and PTSD survivors who saw themselves in Tony, and needed that representation of their pain to have a happy ending... all the people who found solace in the idea of Irondad... could live in a world that's that much brighter.
What did you think of the end of Endgame and this fan theory?
Do you think it was a fitting end to Natasha and Tony's stories, or do you wish it had gone differently?
Do you agree with my theory, or did you see a hole in it?
I look forward to reading your comments.