When Buffy and the gang discover a nest of vampires, they turn to Jonathan for help. At Giles' apartment, Jonathan examines weapons and practices hand-to-hand combat with Buffy. Willow uses her computer to find a way to attack the vampire nest, but Jonathan finds a better way. He slays the majority of the vampires, leaving Buffy feeling inadequate, having allowed one vampire to get by her.
As they leave the crypt, Jonathan poses for pictures. He senses Spike hiding in the shadows, and then Spike emerges. Buffy is at a loss for her usual witty puns, but Jonathan steps in to knock Spike's confidence down. While putting pictures of Jonathan up on a wall, Willow and Tara talk about the fight earlier that night and Buffy's damaged relationship with Riley. At Riley's dorm room, Buffy tries to play basketball, but she is too uncomfortable around him to let him get close.
Jonathan comforts Buffy and he tells her that she's mad at Riley because he doesn't know her as well as she'd like him to. He tries to convince her to forgive Riley because her expectations are too high. All the while, Jonathan signs autographs for overzealous fans. Colonel George Haviland is the new commander at the Initiative, but Jonathan takes over and explains the plans to find and destroy Adam. One fan, Karen is spying on Jonathan's house, but is attacked by a demon and manages to run away.
Jonathan counsels Riley about his relationship with Buffy, then shoots at apples atop of the heads of Initiative operatives, while blindfolded. When Jonathan takes center stage as a singer at the Bronze, Buffy and Riley take to the dance floor. As Jonathan plays the trumpet, Xander and Anya are inspired to go somewhere to have sex. Buffy tells Riley that she wants to move on with their relationship. Karen goes to the Bronze for Jonathan, and when she is taken back to his place, describes the demon's appearance. Jonathan acts strangely when she draws a symbol she saw on the demon, but he dismisses it as a harmless monster.
Adam realizes that something is wrong with the world, and that Jonathan isn't supposed to be this popular, but decides to see how the situation develops. When twin blond girls call for Jonathan to come to bed, he drops his robe to reveal a symbol on his shoulder that matches the symbol Karen drew. On Tara's way to her dorm room, the demon attacks her. She chants a spell and escapes with her life. The next morning, Tara identifies the demon by the symbol on its head, and Buffy has even more reason to question Jonathan.
Buffy stops by Xander's, and finds Anya and plenty of things on Jonathan. Buffy questions how Jonathan could be so perfect. He is credited for all the great things that have happened in the world (starring in The Matrix, inventing the internet etc.). Riley encourages everyone to follow Buffy's lead. They look at Jonathan's swimsuit calendar to see the monster's mark on Jonathan's shoulder. Jonathan arrives and explains that he has a history with the monster and every time he faces it, he is overcome by confusion.
Buffy and Jonathan get information on the demon's location from Spike. Willow discovers that Jonathan did an augmentation spell that would make everyone adore him, but that the spell had the side-effect of creating a demon to balance-out the positive changes to Jonathan's life. If the demon is destroyed, the spell is reversed. The gang has a hard time dealing with the prospect of a world without Jonathan.
In a cave, Jonathan tries to prevent Buffy from falling into a pit, but the demon interrupts them. Jonathan hides while Buffy fights the demon, then runs out and pushes the demon into the pit, nearly falling in himself but being saved by Buffy. With the demon destroyed, the world goes back to normal, and Jonathan is once again ignored by everyone. Jonathan explains that when he received counseling after his attempted suicide, another guy informed him about the augmentation spell, skipping the part about the demon.
Buffy and Riley are kissing on his bed, until she moans, "Jonathan".
"Superstar" can be seen as a spoof on Mary Sue fanfiction, in which an idealized version of the writer is inserted into a fictional universe and upstages the established characters. Jonathan, a peripheral character, becomes nearly omnipotent, universally adored and admired, and even takes Buffy's place in the opening credits.
Buffy's character is severely affected by Jonathan's augmented universe: most or all of her previous slayer feats are now credited to Jonathan, and Buffy's position and persona are demoted from confident leader to nervous sidekick. Throughout the episode, Buffy quickly gains confidence in her abilities as a slayer, and through her actions also gains that confidence from the others.
The title sequence is generally constant throughout each season, except when the regular cast changes. This episode has a specially modified title sequence that contains about 10 shots of Jonathan performing heroic acts such as defusing a bomb. The end of the sequence is a shot of Jonathan with a flowing coat, similar to that worn by Angel, replacing the usual shot of Buffy triumphant. In spite of Jonathan's prominence in the sequence, Danny Strong is not featured as a regular cast member.
Jonathan-related merchandise seen in the episode includes a number of Jonathan comic books published by Dark Horse Comics, the real company that publishes comic books based on Buffy the Vampire Slayer.
Danny Strong lip-syncs the song that he sings at The Bronze ("Hey Sonny / Serenade in Blue / Trapped" by Royal Crown Revue). Brad Kane, who played Tucker Wells in "The Prom", provided the vocals. While playing the trumpet at the Bronze, however, Strong was actually synching the notes, fingering it as instructed by a family member.The immediate prequel to this episode is Jane Espenson's Buffy comic, Jonathan.
Some time has passed between the previous episode and this one, Tara has been introduced to the rest of the gang, and she now associates with them socially; although the romantic nature of her relationship with Willow is still secret.
This episode introduces Jonathan's dabbling in magic, which will play a major role in season 6.
Jonathan helps Buffy and Riley overcome issues raised in "Who Are You".
Jonathan reveals Adam's weakness (his uranium power source), although this is not mentioned again until later in the season, well after Jonathan's spell is ended.
Jonathan's spell establishes how easily reality can be bent to an extreme degree, setting a precedent for the sudden integration of Dawn in Season 5.
This episode introduces the world without shrimp and the world entirely of shrimp. The former will be referenced again in "Triangle", and the latter by Illyria in the season 5 Angel episode "Underneath".
This is also the first time that Xander performs a spell by himself, showing how easy it is.
A comment made by Riley about a spell allowing the caster to "turn an enemy inside-out" is a possible allusion to the fate of "Trio" member and friend of Jonathan's, Warren Mears, in season 6.
Buffy's curly hair was seen in the previous episode and she wears curly hair in the next episode "Where the Wild Things Are", then in "New Moon Rising" and finally "The Yoko Factor".
"Superstar" was first broadcast on the WB on April 4, 2000. It received a Nielson rating of 2.8 on its original airing.
Noel Murray of The A.V. Club gave the episode a mixed review, stating, "So many big and small details are different in Jonathan’s version of reality, and yet the significant elements of the season-long story arc are still in play. In my head, I can make sense of all this, but I still can’t help thinking that “Superstar” would’ve been better if it had been a true standalone episode, with no link to the main storyline."
A review from the BBC website was positive, stating, "Superstar feels like Buffy's fourth season cruising in top gear... It's a great idea, immaculately executed, which is full of the usual witty in-jokes."