Guest is Stiles sister and you are 19 and Stiles is 16 and you and Derek don't like each other, but you do have a thing for older men.

Danny: "Who's he again?"

Stiles: "My cousin... Miguel"

Derek looks up at Stiles with a glare then back at his book he's reading (or pretending to read)

Danny: Is that blood on his shirt?

Stiles: "Yeah... he gets these horrible nose bleeds. Hey Miguel I thought I told you you could borrow one of my shirts."

Derek looks up at Stiles and closes the book and stands up, walking to Stiles drawers to find a shirt and takes of his shirt and just then you walk by Stiles open room door