Folk is here! Well, that may or may not be a good thing. Let's find out together shall we?!
I don't know your grade level so this may not be an appropriate suggestion but one of the major themes in twilight that you could talk about is the parallel between vampirism and sex.
Basically when steph is talking about being bitten by a vampire and the way she has Edward wanting to wait until he and Bella are married, she is really talking about premarital sex. Try reading a passage of twilight where they're talking about Bella becoming a vampire, plug the word sex into the spot where it says bitten or becoming a vampire. It won't look great grammar wise but I think that it will give you a good idea of what I'm talking about.
You can also talk about what it means to be human. That topic comes up a lot in this series although, oddly, Steph doesn't really dive as deep into the subject as she could. That might be because she wants to keep from pressing her own beliefs on her readers. However, the fact remains that the characters themselves do have to decide if being a vampire really means you are no longer worthy of a soul.
Think about it this way, do you think a lion is damned because it eats a zebra?
It's pretty much the same thing if you put a vampire in place of the lion and a human in place of the zebra. It's more like a fact of nature to me. Humans have always found ways to avoid our natural predators. So maybe nature finally created one that we couldn't get rid of with technology or medicine.
That's my opinion so of course you can use my same points to argue against vampires and their nature if you want. But I think those might be some good topics to start with.
I hope I was able to help. If not, let me know some more details about the paper and I'll see if I can come up with something better.