Kate McKinnon guest stars as the voice of Peter's older sister, whom Peter doesn't like because she bullies him and who comes over for Thanksgiving dinner. Initially, seeing Peter get what he deserves for bullying Meg is great...until things go too far and Meg decides to help Peter fight back.
Tropes:
- Ambiguously Gay: Karen is portrayed as a gruff, unfeminine tomboy and is voiced by the openly gay Kate McKinnon. She makes a joke at one point about trying to woo Lois in the past, but it's not confirmed if this is true or not.
- Bait-and-Switch: An infamous one takes place during this episode. When Meg complains about Peter being beaten up by his sister and everyone else is just standing by and watching "like the whole world during The Holocaust", the viewer expects this to be followed by a Cutaway Gag making a tasteless joke about the event. Instead, it's followed by Peter standing in front of a black background, saying forlornly, "Too true...never again."
- Because You Were Nice to Me: Peter's reason to treating Meg better.
- Big Damn Heroes: Meg comes just in time to save Peter from getting his ass handed to him by Karen.
- Big Sister Bully: If we assume she's older, Karen was this to Peter and treated him much the same way he treated Meg.
- Brawn Hilda: Karen, and how. She's a big, burly woman who is tomboyish, rude, and skilled at wrestling.
- The Dog Bites Back: Peter attempts to do this by showing Karen up at her own game. He instead gets his ass kicked. However, Karen is left in a coma after Meg hits her with a chair, and the doctors inquire about a possible transplant. Peter doesn't know if he's a blood match, but he explicitly says he's not interested in checking to find out.
- Double Standard: Abuse, Female on Male: Subverted. Karen's bullying of Peter is seen as playful/karma for his treatment of Meg. But it is clear Peter is deeply traumatized from what Karen put him through and even Meg feels pity for Peter.
- Everyone Has Standards: After Peter gets the "toxic shock", stutters, and pees his pants, everyone is noticeably shocked (including Meg, who found Peter being bullied by Karen cathartic up until this point).
- Freudian Excuse: Having Karen as a sister made Peter the way he is towards Meg.
- Generation Xerox: Meg quickly figures out Peter and Karen's dynamic, due to knowing what it's like to be repeatedly abused by a family member and no one else in the family doing a thing about it.
- Green Means Natural: A cutaway gag sees Stewie doing an ad for Monster energy drink. Jittery, rambling, and hyped up on the drink, Stewie says "It's green, so it's nature!" to upsell the drink.
- Horrible Judge of Character: Lois forces Peter to be nice to Karen when she arrives, regardless of her bullying him.
- Laser-Guided Karma: Karen ends up in a coma (courtesy of Meg hitting her with a chair), with it even being implied at the end of the episode that she could die without a blood transfusion that Peter refuses to be the donor for.
- Last Request: Thinking he's about to die, Peter says Stewie is in charge of the show when he's gone. Peter survives at the last moment, but Stewie didn't get the memo, so he arrives dressed as a pimp and escorting a hooker.
- Murder by Inaction: Peter decides to just let Karen die by refusing to be her blood transplant donor.
- The One That Got Away: Karen makes a quip about Lois being this to her.
- Poor Man's Porn: Chris asks for a flyer of Hispanic women running for city council. When Meg has one, he takes the flyer upstairs. He later invites the city councilwoman over to Thanksgiving, clearly attracted to her.
- Retcon: Peter having an older sister has never even been hinted at before Karen's appearance in this episode. Previous episodes have always indicated that Peter was an only child, and even episodes released after "Peter's Sister" include flashbacks to Peter's childhood that don't show or mention Karen at all.
- Sudden Downer Ending: As the family reconciles the lesson Peter learned about standing up for himself, he reveals Karen is in a coma from Meg hitting her with a real chair instead of a stunt one. He gets a call from the hospital urging him to donate for a blood transfusion which he apathetically refuses, leaving his sister to her fate.
- Useless Bystander Parent: As Peter tells Meg, Thelma and Francis used to sit by and let Karen pick on him.
- Villain with Good Publicity: Karen is a popular professional wrestler, and while she may not be an outright villain, she's portrayed as even more of a Jerkass than Peter is.
- Wham Episode: After Meg saved Peter, Peter doesn't bully or harass her as much as he used to.
