Snow White
Severus Snape first heard the story of Snow White when he was ten years, seven-and-a-bit months, and thirteen days old, and sitting in a lovely green glade overshadowed by trees and sparkling with dew where a red-haired princess (beautiful in the way some children are, with promise and hope combined with genetic chance) told him, eyes sparkling, of a wondrous world where a poor, beautiful girl, hated by her stepmother, but kind and gentle nevertheless, ran away to the woods, and lived happily ever after (and I mean, really really, Severus,) with her prince.
Even then, he knew it was ridiculous.
In the real story, the prince doesn't kiss Snow White back to life.
In the real story, nothing can raise the dead.
In the real story –
He's always too late, with nothing to do but mourn, not even given the privilege of seeing her face through a glass coffin because she's beneath the ground and she rots.