That’s pretty easy again, and not only because there’s not that much to pick from - Prophecy Girl.
This is the first episode that is written and directed by Joss Whedon, and that shows. If you can ignore the still terrible music, it’s the only episode of season 1 (except maybe ‘Angel’) that could easily belong to a later season.
I love it because it is really the turning point for Buffy. Until now she did her job, struggling with the repercussions on her life, but still doing it out of reluctantly feeling responsible for the world. But right here in this episode she wholeheartedly accepts that it’s her fate to save the world and eventually die for the cause, that it’s the mission that counts, something that from now on will underlie everything she does, no matter her struggle not to let it rule her whole life. And what is it that after the initial refusal to sacrifice herself makes her change her mind? The love she feels for her friends and family - it’s her mother’s unwillingness to go away with her daughter and Willows anguish that in the end drive her to fulfill the prophecy.
It’s the very first episode that hits really hard emotionally, and Sarah Michelle Gellar knocks it out of the park. Her reaction when she overhears Giles and Angel talk about her prophesized death, her frantically trying to convince her mother to flee with her, her sad determination when she talks to a devastated Willow hurt to watch, as does seeing her scared for the first time when she is down in the caves to find the Master, but bravely goes on, and then hearing that it’s her blood that will set him free.
I love that her living differently than intended by the Watcher’s council, namely having friends, is not only the reason for her to accept her role, but also in a brilliant turn saves her! Beside the confidence boost after having proved the prophecy wrong, I always saw this as the main reason for coming out stronger than before and eventually defeat the Master.
This is the episode in season 1 with the most character growth, and not only for Buffy. Willow gets to stand up for herself, telling Xander off when he asks her to be his date after being rejected; and Giles really comes through for Buffy, ready to sacrifice himself to save her life (before he gets knocked out :) ). To me it marks the turning point in their relationship where Giles begins to become her surrogate father.
The symbolism used throughout the episode is also brilliant – rejecting the cross (the christian symbol of sacrifice) Angel gave her as a present in the first episode when she refuses the sacrifice, then picking it up again when she accepts it; her being led to the cave by a child, representing her childhood that she loses when the Master kills her; and of course the use of blood equaling life that gets picked up heavily in season 5.
It’s this episode that closes the book of Buffy childhood with a bang forever and sets her on the hard path of adolescence. I love it.