It's Grace.
Soundcloud of this theory for those who would rather listen: https://soundcloud.com/matthew-enthoven/fall-from-grace-scream-queens-theories-after-black-friday-episode
Seriously, go back and watch the show knowing from the start that Grace has been tricked by Gigi to believing that she was bathtub baby and trying to "purify Kappa" to avenge her mom.
STAY WITH ME FOLKS - THIS IS FUCKING BRILLIANT!! I just rewatched the first three episodes AND IT IS SO FUCKING BRILLIANT I CANT BELIEVE IT AHHHHHHHHHHHHHH!!!!!!!
My evidence?
Every.
Scene.
Changes. with this explanation.
The show was so brilliant. It's been written to be watched twice.
Stay with me!
It starts with this: Before arriving on campus, Gigi lead Grace to believe that her mother was the bathtub baby. Gigi, Boone, and Grace had already hatched a plan to avenge her mother by ridding the house of the Channels.
First episode, Grace is in the coffee shop when Chanel and Maid are discussing the fryer plan. Grace is the one who turned the fryer on. She and Boone also set Grace up with the pictures in the Maid's room, giving Chanel motive. She tries to go to the police, but then Chanel gets the pledges to back her up. Grace is trying to frame the head Chanel so that there's a gap for someone to take over but it fails. Pete sees Grace and the Chanels trying to dispose of the body.
Pete and Grace meet in a coffee shop. Grace literally says in this scene "I want to destroy the Chanel sisters and restore the Kappa house to avenge my dead mother." It was right there the whole time!
This launches the investigation into the Kappa House. At one point, they break into Dean Munsch's office to look at files, and Red Devil Killer knocks out Pete and leaves him alive with a sign of "Mind your own business." Grace was right there in the office with Pete, she put on the costume and knocked him out. One of two people that RDK has left alive, because Pete has been so pure and wanting to help her take down Kappa house. The other one? **Zayday, another pure person who was doing too much snooping**, and someone that both Boone and Grace liked. So they kidnapped her to try to keep her safe.
While in the office, Grace gets the blueprints to the house and learns about the secret passages.
As the investigation continues, Grace starts becoming more and more suspicious of what happened to the bathtub babies. Things start to conflict with things Gigi has told her.
Grace confronts Gigi in the kitchen about some of the things she has learned. She's very suspicious, but can't prove that Gigi is lying**. Gigi mentions that they got proposed. Grace goes to her father and learns that her dad didn't propose, and gets even more evidence that Gigi is lying and manipulating everyone.
And it all culminates when Chanel confronts her. Chanel literally says to Grace "You thought you were the baby in the bathtub, so you came back to KPT to murder everybody. But guess what Grace? You're not the baby, so you can stop murdering everybody."
Everything unravels when Grace learns she's not the bathtub baby - she learns she was tricked into committing such horrible crimes.
Grace starts to come to terms with the fact that she's been lied and manipulated too. Maybe she figures out that Grace is the bathtub baby here. She feels bad for Chanel in the coffee shop, which is why she'll later hesitate to kill her in the mall. She also thinks the apology is a moment of redemption - maybe Kappa house can be saved without murder by creating a genuine, everlasting sisterhood.
Grace and Boone make a plan to kill Gigi, to get back at her for all the lying and manipulation. But before they can, Pete figures everything out.
Pete continued his investigation and found Boone, and he posed as the Red Devil Killer in the Gigi/Boone confrontation. Boone and Gigi admit everything in their confrontation, with Gigi literally saying "a plan 20 years in the making."
Pete starts to do more investigating about Gigi and starts to investigate Grace's Dad.
There are a few different ways the Thanksgiving accusations could have happened, but they don't have definitive proof yet. One thing doesn't make sense - Gigi clearly indicated that the RDK was Boone's brother, so Pete would have naturally ruled out Grace unless Pete suspects that Grace's father is "in" on the whole thing.
Pete starts to do more investigating about Gigi and starts to investigate Grace's Dad.
Dad accuses Grace of being the killer, and he believes it. He doesn't want it to be true, but he believes it.
Pete goes and gets the DNA test to find Dad is the father of Bathtub baby. He accuses Dad at Thanksgiving because he thinks that Dad and Gigi were in cahoots. But Dad is innocent, and so in Black Friday, he insists on sitting down with Pete and talking things through. This is where they start to piece together that Grace is the actual killer.
And maybe Grace's Dad did kill someone to try to protect his daughter. Maybe he's starting to find solace too. Gigi manipulated him as well. And he's so in shock. All his reactions from Thanksgiving on are pure shock, like "oh shit, what have I done, none of this makes sense."
All three of Mr. Hudson's children are murderers. (More on this in a sec!)
Up until this point, Grace had assumed that Gigi killed Boone. It makes sense - Gigi called saying "we have to get rid of him." So Grace's revenge plan is still on. She's going to kill Gigi for all the lies and manipulation, and for trying to get her to kill her partner (Boone).
Gigi says to Grace in the Red Devil Costume "You killed your brother", which makes Grace suspicious and leaves her very confused, so she delays killing Gigi slightly. She knows she didn't kill her brother, which means that someone is onto them. She also knows there's another Red Devil out there - those three didn't kill Munsch's husband, so they know someone else is pretending to be them.
She also starts looking for a way to end it all and frame someone else as the killer. She frames Munsch. Gigi, Boone, and Grace all knew that none of them killed Munsch's husband, so pinning everything on Munsch may have been the best move. Gigi hated Munsch. So Grace has a whole bunch of circumstantial evidence that Munsch killed her half-brother, Boone, and killed her husband.
Her speech to the Kappas on killing Munsch plays to her motivations - Grace wants to be redeemed herself. She wants everything to have been worth it.
She says "I have been talking all year about how I want this house to become a true sisterhood. I've always had this vision of a band of sisters who stand together like an impenetrable community of shields who kept everyone safe and secure." She's trying to lay out her moral authority for not just killing Dean Munsch, but all of the crimes she's committed so far.
Later, Pete and Grace's dad have figured everything out. They're convinced it's Grace, but they're trying to find some way to save her. They both care deeply about her. But Pete's suspicions start to show, and Grace starts to know it.
The confession at the end of Black Friday is that Pete killed Boone.
Grace now knows that Pete knows. When she sees Pete packing, she knows it's all unraveling. She really loved Pete because he was so pure. He told her in the first episode that Kappa was full of monsters. He refused to join a frat. He's the definition of moral purity, and yet another justification for the murders - "you agreed that Kappa was monsters!" She's been holding back sex up until this point because she has something on her body that gives her away. She throws herself at Pete as the "final test."
Pete knows it's Grace, and he's so nervous in the final scene. He just wants to survive because he knows he's with a killer, so he thinks that by admitting he killed Boone, Grace might think "oh shit, he doesn't know it's me, because if he did, he wouldn't tell me that."
I think Dean Munsch also knows. I think Munsch had bugged the Kappa house. That's how she knew to take the antidote, and how she knew how to survive the cryo chamber, and how she learned about the absolutely ridiculous drowning plot (Rasputin, lol). But now Dean Munsch also knows that Chanel is just as bad - she's now tried to commit TWO murders.
Dean Munsch loves the girls and is actually there for the protection of the university, so she keeps trying to save them. She tried to keep them all in Kappa because she knew they were all innocent. But then Chanel crosses the line. Who knows how she'll react in the finale?
At this point, you're probably asking yourself Ok, so if Grace is the RDK but NOT Bathtub baby, who's the Bathtub baby?
I think it's Chanel. And that Chanel, the most unlikely character in the whole bunch, has actually been leading the Kappa house towards redemption by being redeemed herself. By not falling into the terribleness that the Kappa sisters were so known for. She's showing that she can be a better person with events like apologizing to Chanel, or standing up for herself and Hester at Thanksgiving.
Chanel's past is rocky, too. Her mother is an alcoholic. She probably turned to alcohol to deal with the death of her Kappa sister and suddenly becoming a parent. And now, Chanel's a murderer, trying to kill Dean Munsch.
All three of Oliver's kids - Boone, Grace, and Chanel - all three are murders.
Boone's obsession with knives helps sort out the killings. Boone kills Chanel #2 with a knife. He also kills Mandy Greenwell with a knife. He kills Shondell with a knife. He kills Earl Grey with a knife. He kills the Truck Driver with a knife. And he brought the knife to kill Gigi.
Flashback to bathtub at the end of the pilot (technically episode 2) - Girl holding baby says "we're all going to pay." Explains a huge part of the motivations - they're avenging their mother by trying to kill everyone who was involved and redeem the house.
Going into the finale
Grace knows that Pete knows.
Pete knows that Grace knows.
Grace's Dad can't believe it.
Chanel knows that Dean Munsch knows.
Dean Munsch knows **everything** and is trying to clean it up and keep the girls safe.
Stuff I still don't know:
- What were Gigi's motivations for this whole thing? It seems like Gigi was, in fact, the mastermind. Maybe it was just to destroy Dean Munsch, but more than kill her, but *destroy* her. They wanted to frame her as the Red Devil Killer the whole time. But when they realized it wasn't working, the three tried to just kill her (and failed).
- What will Grace do? She's been trying to wiggle out of this whole thing.
- Was Grace's Dad at all involved? It could be that Gigi had also manipulated Grace's Dad somehow. Which might be why he's so in shock. He murdered someone to protect Grace, and then he learns that Grace was the murderer!