After Snape told his Potions students, "I hope you can all brew effective antidotes, because I secretly poisoned some of you over the past few days, and it will take effect tonight," the students spent a tense and thrilling evening.
Not every student believed the poisoning claim, but quite a few did.
Many had at least two bottles of antidote at their bedsides. Some clever-but not particularly clever-students prepared bezoars instead, even though the things tasted revolting.
"If I die, bury me at sea," a student who aspired to become a naturalist told his friends as he wrote his will. "Let the fish carry my ashes around the world. Don't forget to write this clearly on my gravestone-'A warrior unafraid of tyranny.'"
He felt certain he would die tonight, because yesterday he had happened upon Snape showing favoritism toward Slytherin, and before Potions ended, he had received a cold, warning look from Snape-clearly a death notice.
"Even if Snape really did poison you, you won't die." One of his roommates was busy with an essay and spoke without looking up, his voice perfectly level. "I got an O in Potions last year."
"What? Then I wrote my will for nothing?" The student spread his hands in dismay, thought for a moment, then brightened. "Would anyone like a Christmas present wrapped in a will?"
"You could give it to Snape."
His roommate said helplessly,
"If you really don't want to live, that is. At least finish your last Christmas first, all right? Otherwise, I'll have prepared your Christmas present for nothing... Why are your eyes so wide?"
"You actually got me a Christmas present?" the student said in surprise. "Good heavens-"
"...So you didn't get me one?" His roommate's gaze turned dangerous. "Looks like congratulations are in order-your will wasn't a