When Remus Lupin was fifteen, a stag, a dog, and a rat joined him in the Shrieking Shack and helped him survive the terrible night each month.
What none of you know – what none of them knew – is that before the three animals came to be, Remus Lupin was joined by another animal: a cat.
A cat who would sit with him every month and ensure that he was all right.
Didn’t you ever wonder why she became an Animagus?
oH
Oh my God McGonagall is the best thing that ever happened to Hogwarts.