Evil Librarian by Michelle Knudsen

Book 1

When Cynthia Rothchild's best friend, Annie, falls head over heels for the new high-school librarian, Cyn can totally understand why - he’s really young and seriously hot and apparently thinks Annie would make an excellent library monitor. 

But almost immediately, Cyn starts to sense that something about Mr. Gabriel isn’t quite right. Maybe it’s the creepy look in the librarian’s (literally) mesmerizing eyes, or the weird feeling Cyn gets whenever she’s around him, or the blood and horns and giant bat-like wings that appear when he thinks no one is looking. Before long, Cyn realizes that Mr. Gabriel is, in fact…a demon. 

Now, in addition to saving her beloved school musical (Sweeney Todd!) from technical disaster and avoiding making a complete fool of herself with her own hopeless crush (who happens to be the only other person who knows the truth about Mr. Gabriel), Cyn has to save her best friend from the attractive-yet-very-very-bad clutches of the evil librarian, who has not only bewitched Annie but also seems to be slowly sucking the life force out of the entire student body!

Excellent condition.