"School Hard"

The leaves are changing color, the air is cooler, it must be time for... the Night of St. Vigius. Once again Buffy's life is in danger as the Master's minions seek to gain extra power by killing Buffy during a sacred holiday. But Buffy's mind is not on slaying. She and Sheila, a perpetually bad student, have been threatened with expulsion by Principal Snyder. The only chance they have of staying in school is to help organize Parent Teacher Night.
While Buffy plans this evening, a new demon is in town -- Spike, a 200-year-old vampire who has actually killed two slayers over the past century.(You also meet a very cute, but weak, vampire named Dru. You learn her story later on.) Giles urges Buffy to take this challenge seriously, but she is preoccupied with her school project and trying to cover for the never-present Sheila.
When Parent Teacher Night arrives, Buffy unsuccessfully tries to keep her mother away from Principal Snyder. But things become a bit more serious when Spike and some other vampires crash the event. The faculty, and Buffy's mom, think these are just some gang kids on angel dust. Buffy convinces her mother to stay hidden while she faces the vampires. Giles tries to help Buffy, whose biggest worry is about her mother's safety. No-show Sheila finally arrives and -- surprise! -- she's a vampire too. Angel (who just happens to be Spike's sire) tries to help by pretending he's on Spike's side and offering up Xander's neck for a snack. Spike isn't fooled and becomes enraged. Buffy continues to battle Spike until her mom's maternal instincts overtake her fear and she whacks Spike with an axe. Spike flees. Much to Buffy's relief, Mom is not angry about Principal Snyder's assessment-- she's proud that Buffy is so resourceful and thoughtful of others in a crisis.
When Spike returns to the lair without having killed Buffy, the Anointed One is angry. Spike throws the child into a cage and raises it up to the light. Suddenly the cage is empty and we see only a puff of smoke, as Spike and Drusilla go off to watch TV.