Links: 

I've Got a Theory - 0:05 

[It's so short that an instrumental isn't really necessary]

Character:

Buffy's best friend, and a powerful witch. Generally very friendly and goofy at times. She brought Buffy back to life a few weeks prior and she's extremely proud of it (and a little bit cocky). Others like Giles, and her girlfriend Tara however are concerned that her use of magic is getting out of hand! Her speaking voice is mid-high and she has an American accent. She doesn't have too many lines in this episode.

Singing:

She has very minimal solo singing parts, but she will have to sing in a chorus. Doesn't particularly have to be a strong singer as long as she can hold a key.