Anybody who takes any of his classes knows this stuff. He's not a nice guy, but he's a good teacher.

[Ellie can't believe she's defending him like this, but every word of it is true. And Ellie may be the first to call Snape a power-tripping dick, but one of Voldemort's lackeys doing it isn't sitting well with her.]

And besides, if they wanna find out who he really is? They should be figuring that out for themselves.