A/H Spike is Dawn's dad, Buffy goes to school with her. (ETA found -- thank you!)

Been looking for this forever. Buffy is the new kid in school. She makes friends with Dawn. Dawn never brings any of her friends home because they hit on Spike all the time. Spike and Buffy had hooked up when he went to LA -- he met her in a club and thought she was older.

I am 90% sure I read it on SR but haven't been able to find it.

I think it's this one.

Father Knows Best by TammyAsh666

http://spikeluver.com/SpuffyRealm/viewstory.php?sid=34251&warning=NC-17

Summary: Dawn Pratt is tired of all her friends having a thing for her father, so she stops inviting them over to her house. She takes a chance on Buffy Summers, a new friend of hers, not realizing that was the one girl she never should have invited over.

Yes that is it -- Thanks!

YW.