The spirit of Hogwarts feels Harry needs protection. Dumbledore isn't doing a good enough job, so she calls on the only man she feels can get it right. Prophecies fear him, demons flee from him, and Slayers love him. Enter Xander Harris. Original story, Potter's Protector, is written by mjimeyg.
Being the Slayer on the Hellmouth, dying once already at the hands of the Master – you could say Buffy Summers is fed up with destiny. Just averting another apocalypse by stopping Acathla from bringing hell to Earth through Angel...will the final nail in her coffin be the Wizarding World? A hidden society with actual magic wands, flying brooms, goblins, trolls, and no-nose baddies?