I haven't read Twilight. Lydia said it wasn't worth it and I fell asleep during the first ten minutes of the movie.

[So just ... putting it out there.]

Also I'm pretty sure they were a horror movie trope first.

[Also just saying. But okay. Redirecting to what a werewolf is. How does she actually explain it in ... general terms with no pop culture references.]

Basically we can change our shape. Werewolves can't go all the way to an actual wolf without going through this weird rite of passage thing, but they can do the halfway shift with the claws and the fangs and the ...

[And then there will be a snarl, complete with slightly threatening gesture, but she doesn't actually lunge because she doesn't want to scare her.]