Potential

Buffy has not been called as the slayer, and Merrick was training her as a potential when he died.   Giles has been sent to Sunnydale to research the Hellmouth.   Buffy and her mom move to Sunnydale, and soon Buffy has a crush on Giles.   Sometime after her eighteenth birthday, she and Giles realize that there is a connection between them and start to date.   Then she is called as the Slayer.

Required:
1. Buffy and Giles fall in love before she is called as the Slayer.
2. Giles trying to convince the Council that Buffy shouldn't be the Slayer.
3. The Council reluctantly asking Giles to be Buffy's Watcher, since he's there already.

Options:
1. I picture this starting during Buffy's senior year of high school and continuing into college, but you can start it after graduation or with her in college.
2. You can have Giles accept being her Watcher or bring in someone.
3. Any rating is fine (G to NC-17).

That's it. Have fun with it.