Okay, maybe allegory is too literary of a term to call Buffy. It is not an easy show to categorize. It has monsters, but it is rarely gory or horrific. It has comedy, but no laugh track. It has boyfriends, girlfriends, and dating woes, but does not descend into soap opera corniness. A lot of the same elements one can find in memories of high school. The reason why this series is so popular is it can use these elements and a cast of great actors to address issues without becoming an after school special.
One issue that has almost become an underlying theme to the series is popularity--who has it and who does not. The first episode to see things from both the in-crowd and the outcasts points-of-view was "Invisible Girl (a.k.a. Out of Mind, Out of Sight)." By using the fun elements of the show--the Hellmouth, the sarcasm, and the characters--Joss Whedon writes a story that highlights the pain of high school.
The opening scene draws the line between the two opposing social camps quickly. Cordelia's conversation is the stereotypical concerns of a California valley girl. And as many other superheroes could tell Buffy, maintaining a secret identity and saving the world once a week wrecks your social life. (Show 0:00 - 5:14)
Buffy's best friends in Sunnydale are Xander and Willow--both social outcasts. Willow is a nerd who loves school, but no one outside of the gang and the audience can see her kind and compassionate nature. Xander is just ... Xander. Boys think he is a wimp and girls give him the brush off, but no one really knows why. As they make fun of Cordelia, Buffy explains how she used to be just like her--until the reality of being the Chosen One for her generation forced her to grow up in a hurry. The audience can see how much Buffy misses that life, even if Xander and Willow cannot. (Show 9:13 - 10:52)
The monster is introduced by beating up Cordelia's boyfriend, Mitch. It leaves a message at the scene: LOOK. The gang starts investigating, because anything that has the potential to decrease the student population needs to be dealt with. Harmony, Cordelia's best friend, is pushed down a flight of stairs. The gang realizes they are looking for an invisible person; one that has a murderous grudge against Cordelia.
The second flashback of the episode is the first one where the audience sees Marcy. She is trying to push her way into Cordelia's circle only to be insulted and then ignored. Cordelia makes this worse by commenting on the observation Marcy has made three times. Marcy laughs along with the group, but her large grin fades as she is left behind once again. (Show 21:18 - 22:24)
Cordelia is elected May Queen, but no one is really surprised. The gang discovers that Marcy Ross was the latest addition to the dead or missing students list, and no one remembers her. Buffy finds the invisible girl's hideout in the ceiling above the band room and her yearbook. A teacher is attacked. Cordelia finds her before she suffocates and watches Marcy write another message: LISTEN.
The group conference in the library is pivotal to understanding Marcy. The question of why she is invisible is answered, but more importantly, we learn that Marcy was the outcast of outcasts. Even Xander and Willow, who have been snubbed and ignored by Cordelia's in-crowd, failed to see her. Ultimately, Marcy is the one who pays for all of this by losing her visibility. Cordelia finally puts two and two together and comes up with someone is after her. So she comes running to Buffy for help, with a surprising logical reason behind it. (Show 27:31 - 31:08)
The conversation between Buffy and Cordelia shows a new side to Cordelia, one that has not been revealed in the series before now. The audience is shown that Cordelia has the potential to become another Buffy, to realize what true friendship is, and to have the courage to leave the phony self behind. (Show 33:48 - 34:37)
Of course, Buffy defeats Marcy and the status quo returns to normal. The gang tries to make an overture of friendship to Cordelia, but she turns them down. She is not ready to admit the truth yet. It is one of the most powerful lessons of the show that popularity can be just as lonely as vampire slaying. Another is that as you grow up, the petty concerns of who is a social loser and who is not become less important. And no one preaches this to the audience. Giles does not stand up in the library and lecture anyone on their short comings. High school is the time in your life that you learn this for yourself.
Hopefully, no one will tell the creators of Buffy, the Vampire Slayer that they are responsible for teaching the youth of America important life lessons. Let them make their show about a wisecracking vampire slayer juggling a social life and homework while trying to keep Sunnydale High School monster free. Once they realize they have created an allegory, it will not be as fun to watch.