The traumatic disillusioning event that pulls many heroes into angsty cynicism. The Anti-Hero or antagonist of a series actually used to be a hero or maybe even a proto-Messiah, who protected something that obviously needs protection. Location, artifact, or whatever. Anime is especially fond of giving aloof swordsmen a literal Dead Little Sister, but a younger sidekick or occasionally even a Love Interest can also work. Expect a Hollywood Atheist to have one of these to explain why he or she does not believe in God. Examples of Dead Little Sister include: