Corvina takes it with you in the cellar with the lantern turned down, and lists the effects out loud, clinically.
She stops halfway through a word.
CorvinaAh. So that is what it does to the throat. I shall have to correct my notes.
You get her against the wine racks with her hair down and her scar in the lamplight, and she is not a professor for any of it.
She leaves the school at Christmas without resigning and writes once, from a town, with no return address.