Aliens and McCoy save Amanda
I think this was on archive of our own. Sometime into the 5 year mission a pair of aliens that were on the enterprise negotiating or ambassadors being moved. They had wings like an angel and had reality powers (they could grant wishes). Bones was in a relationship with Spock.
The male alien offered Bones a wish but there is a price he has to give something up. And the alien chose the relationship because he wanted in Bones pants. Bones asked that Amanda lived. So everyone but Bones and the aliens forgot that she had died and forgot about Bones/Spock relationship and thought he was still with Nyota. Bones could not say any thing about the wish or there would be severe consequences.