This is so cool! I love how you've realistically brought them to their attitudes in Superstar, where she's annoyed and finally dares to take Spike on (and as another comment said, I love that he's her motivation for standing up for herself) and he's familiar enough with her to touch her. The way you've switched up canon events is really clever, such as having Buffy hit him with the axe and him licking her neck and telling her to deliver the Saturday message. I really like how he blames her immediately in Lovers' Walk and finds her in "The Initiative." Their voices are really great throughout:

“You just yell out ‘come in’ to whoever knocks on you door? You are the most pathetic slayer in history.”

Knowing Spike though, he would’ve just broken the lock.

she harbors the secret desire that he’ll start to be nicer to her.

Awwww.

But it was high time someone else did a little touching in this relationship.

Hee! I'll say.

Not quite a memory, more like a dream she doesn’t fully remember. A flash of his fingers in her hair, or his tongue on her neck, and then it’s gone. She shivers, and tells herself it’s with revulsion.

Such a great ending! Fabulous concept. Now I wonder, how would their relationship have progressed if the Superstar spell hadn't lifted?...