>>99690883>Lots of Skrulls during Secret Invasion were sleepers who thought they were human until the activation signal came in.
I don't know why anyone think it is a good idea to do this in the MCU. The way I see it, doing so to a character basically kills the character retroactively and is not interesting at all.
I mean, hypothetically, you could make a DCEU movie where we found out Snyderman is secretly Bizzaro. But it would just piss off any fans of Snyder by doing this. Taking a loved character and say "just joking! everything in the last few years was a lie!" is not smart film making.
Marvel can afford to do this in the comics because it doesn't cost hundreds of millions to make a paperback. But those who are asking for this in the MCU is just not thinking straight.