Even after he sees her after the first time wince they graduated——and he isn’t surprised, considering she’s always been obsessed with the Dark Arts, the greasy haired slimeball—there is still a feeling in his gut of something wrong.
Until it occurred to him that Snivella thought she was on the right side, and how she smirked when the curse got his right cheek.
(For some they were a lost cause—— but then again, the word ‘Mudblood’ was heard in his mind’s eye and he realized….some things weren’t his fault.)
As Peter took a hit and was on the ground, bleeding, he felt relieved because;