When Harry defeats Voldemort, all those marked by Voldemort lose their magic. Snape decamps to the United States, where he becomes a fry cook in a diner. Five years after Voldemort's defeat, Harry comes to him for advice. AU, obviously, as Snape was still alive when I wrote this story.
EnniNova:
-А Снейп-то, говорят, не настоящий!
- А какой?
- Так черный же!
- Это в каком смысле, черный?
- Во всех!
- Правда? Это точно?
- Ну, так автор говорит. И вообще, истина как всегда, где-то рядом.