It's an alternate universe kind of thing. Drusilla was less than pleased after "Crush". She made a few stops before leaving town. Now, Giles has to learn to cope in a whole new world, while at the same time keeping his old world from falling to Glory.

Rupert Giles lent money to a young man who needed a little push in the right direction. Xander Harris attended college, finished with a degree in criminology, and after Buffy's death, left Sunnydale in the capable hands of Faith and Angel. Willow Rosenberg and Tara McClay chose to stay in Cleveland, while Giles, Dawn and Spike have settled in England. After a stint at FLETC, a friend named Riley Finn recommended him to NCIS in Washington D.C., where he is now a special agent, working under Leroy Jethro Gibbs.

She'd left everything to a mysterious Longbottom great-great-uncle by the name of William with a birthdate somewhere in the ballpark of Dumbledore's.