Ok here are some headcanons I have for Zero, specifically from the Megaman Zero series.

His memories were not so much erased as they were repressed, otherwise he would not have been able to recall them so quickly.

(TW for mentions of trauma) Zero might have been going through a lot mentally during the events of the games, which explains his irritability and tenseness in the later parts, a lot of crazy things like that will mess with you. Not excusing his more questionable actions, but subconscious reliving trauma like that will deeply effect you in one way or another.

This next headcanon is that Zero has not likely to notice at first but still there if you look level of fang bc why not (don't answer that). There's a bit of precedent for this in the X series with a few screenshots, I'm carrying that into MMZ design because I can and I think it adds a bit more scrunkliness to his design. Plus I can draw what I want, as long as it doesn't go against my morals.

(I'm scared to check the tags because I put MegaMan zero in the tags and every single fandom has that side. I'm in the side of the mostly clean community but I mainly do what I want.)