Why Do You Do It? - Sirius Black

Sirius has detention with a curious Minerva McGonagall. Snape happens to walk in on the tail end of their conversation and finds out about something.This is currently a one-shot, but if you want me to do anything or add a chapter let me know in the comments.Also, I've only read the first six books of the series, so don't spoil anything for the last book please. I'm reading it.Hi, this is after I wrote it, I have now finished the seventh book, so the previous note can be disregarded. Also, does anyone want this to have more chapters! If so, ideas? Does Snape tell people, keep it to himself, make his presence known, stay quiet, what should happen next? Thanks for reading :)Let me know what you think :)