This was awesome. I think it flowed nicely throughout it.

He would trade information with Giles and Buffy to keep them satisfied and, as time went by, as an excuse to see her and spend time with her.

On this part here, it's perfectly understandable that you mean Buffy but the sentence seems kind of awkward with you dropping Giles like that. I would suggest the first "her" being "Buffy" to keep that from happening.

Wonderful! I loved the ending. Hee! Pestering!Spike is the best.