I rolled a d10 that goes 00, 10, 20, so on. If I had rolled 10, all numbers below 10 would work. Pets would go in Others, as students are simply allowed them.

For vampire blood, you'd need some more explanation. Perhaps a Gregorovich creation?

The game will be starting after the Sorting Ceremony (I'm not good at rhymes, I don't think I could write a worthy Sorting Hat song).