Harry Potter and the Deathly Hallows (the book) came out nine years ago, so we’ve known for some time now that Snape was a goodie after all.
Keeping it ambiguous for the first six books, J.K. Rowling revealed that although he had once been a Death Eater (in his confused youth), Snape had come back from the dark side (to borrow briefly from Star Wars terminology) after the death of Harry’s mum, Lily.
This was a big shocker, but actually, J.K. had hinted that Snape was good all the way back in book four (Harry Potter and the Goblet of Fire). We just didn’t notice.
If you remember, Barty Crouch Jr. (while impersonating Mad-Eye Moody) had a “foe-glass”: an instrumentthat looks a bit like a mirror, but that isused to show the enemies of its possessor. They appear as shadows, and get clearer the closer that they are.
The first time that Harry sees the foe-glass – when he’s alone with Moody/Crouch – he sees just shadowy figures. Clearly, none of Crouch’s enemies are near enough to really threaten him.
But cast your mind to laterin the story, after Cedric has died and Moody/Crouch has whisked Harry off to his office (intending to murder him). Dumbledore, McGonagall and Snape all burst into the room, and save Harry. And then what happens?
“Harry, still staring at the place where Moody’s face had been, saw Albus Dumbledore, Professor Snape, and Professor McGonagall looking back at him out of the Foe-Glass.”
It turns out that the shadowy figures (Crouch’s enemies) in the foe-glass were Harry’s professors. Including Snape.
Now, surely if Snape were secretly a death eater, working for Voldemort (as Crouch was), he wouldn’t appear in the foe-glass as one of Barty’senemies?
(If you think about it, this makes Snape even braver. The fact that he appeared in the foe glass – as an enemy of a death eater – shows that if Voldemort had ever tried to magically test his loyalty, his cover would have been blown.)
Snape. What a guy.