All Human. Spike is a callboy. Spike thinks Buffy is his customer Darla.

All human. Series
First story
Spike is a callboy. Buffy stays in a hotel in L.A (i think) on a weekend alone, because Hank has no time. Spike is on Buffys hotelroomdoor and thinks Buffy is his customer Darla.
Spike and Buffy spend the night together.

Second Story
Spike(William) go to Sunnydale to his father Giles. And there he meets Buffy again.
Giles doesn't know William is a callboy.

You're looking for PaganBaby's Room Service and the two sequels Coming Clean and Ball and Chain. They are all on this site.

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