dru sends spike out, tells him its time he made a childe

Dru sends spike away, tells him he needs to make a child of his own. He finds a young Buffy and decides that he will turn her on her 18th birthday. Buffy and is not the slayer yet.and falls for spike but he has to leave her to go back to dru . Spike comes to sunnydale to kill his 3rd slayer and finds Buffy

I think you are after Future Childe by Ariel Dawn, sequel Present Childe
Spike, on a hiatus from Dru's company meets a certain blond pre-slayer 15 year old and decides to keep her.

Thank you so much really appreciate the quick response.... you guys have always come throug...

Sraya