Instead of calling up Angel to help Buffy, what if Whistler decided to try and convince Spike to help train her?

Drusilla is dead and Spike is contemplating whether or not to give himself up to the sun. He’s in a bad place, and it gives him more incentive to listen to Whistler’s proposition.

When he sees Buffy, he doesn’t fall in love – instead he sees her potential to be a great warrior and sees someone who needs a friend. Both the warrior and the caretaker in him are drawn to her.

Up to the author how much they stick to canon, but the falling in love needs to happen when Buffy is at least 17.