Crabbe is chattering, but Snape doesn’t want to listen, because he hasn’t gotten any smarter since the first day he set foot in Snape’s classroom, just bigger and craftier and crueler; they all do, the thugs of the world; Snape knows this because he works alongside them, he has since he joined the Death Eaters, and even more so now that they’re running Hogwarts; and he’s so sick of thugs, he wishes they would all just shut up--
“…Potter’s Mudblood mother…”
Snape freezes and Crabbe keeps prattling, unaware of the danger he’s suddenly in as his Professor-turned-Headmaster slowly turns his head to pin him with a black stare.
He notices after a few moments, though, when he sees his favorite teacher looking at him with something that could be mistaken for hate; but of course it is a mistake, because Snape would never look at him like that, he’s his dad’s mate, they work alongside each other; and the look’s gone now anyway; Snape’s smiling at him and saying something Crabbe should probably listen to.
“…going to teach you a new spell, Crabbe. It’s very advanced…” And here Crabbe tunes out as he tries to wrap his head around this, because Snape never teaches Crabbe advanced stuff, he teaches Draco and then if Crabbe is lucky he’ll pass it on to him; but Snape’s still talking and he’s going to have to do without an explanation for now, because both Draco and Snape hate it when they catch him thinking when he’s supposed to be listening.
“…called Fiendfyre. It’s a very violent spell…” And Snape’s still smiling that oddly twisted smile, and he never smiles so Crabbe should be suspicious but he’s too excited by learning something that sounds so interesting, so dangerous, to care much about the expression on his teacher’s face.
“…the best part is, it won’t hurt the caster at all. You’ll be completely safe from it, but only...” And here the smile gets wider. “...only if you cast it in a confined space.” And Crabbe understands “confined” perfectly, because that’s how his mum would tell him he was being punished when he was little; he paid attention when she said it because the “being confined to his room” punishments were far better than the “wait ‘til your father hears about this” ones. Confined. Locked in. Like Draco was locked in that room all the time the year before, he remembers, when he made Crabbe drink Polyjuice and stand guard, does that mean Snape wants him to cast it in there?
With this idea lodged firmly in his mind, Crabbe mimics Snape’s wand movements, completely missing the twisted smile turn into a triumphant smirk.
A/N: Assumptions are fun to work off of. Review or face the wrath of the Ultimate Fan (ie: one who is taking a "Reading Harry Potter" course this semester at college. Yay college!)