Venial Sin (джен)

Примечания автора:
Prompt: AU where Harry does something awful to Snape in retaliation for killing Dumbledore, and then has to deal with the later realization that Snape was on his side (Snape can be alive or dead at that point). Preferably not with a “warm and fuzzy / was only being nasty as part of his cover” Snape.