One of my favorite books of all time and definitely one of my favorite serial killer books is My Sister, the Serial Killer by Oyinkan Braithwaite. I originally read this back when it first came out in 2018, and it’s stuck with me since. But I did a re-listen to it this week, and I loved Adepero Oduye’s take on it. She really nails the sarcasm and brings it to life.
The book is set in Lagos and told from the POV of Korede, a fairly plain, very organized, clean, and meticulous nurse. Her younger sister is a beautiful fashion designer who everyone loves and happens to be a serial killer. Ayoola has the bad habit of killing her boyfriends and then calling Korede to help dispose of the bodies. The only thing that is solely Korede’s is her work at the hospital where she has a crush on a doctor and confides all her secrets in a coma patient. When Ayoola comes to Korede’s work, the doctor takes an interest in her and Korede knows its only a matter of time before Ayoola kills him, too. Korede must decide where to draw the line when it comes to protecting her sister vs. living her own life.
From here on, there will be some major spoilers, so go ahead and read the book if you haven’t yet, then come back.
Enabling the Serial Killer
As I said before, I’ve started concentrating on a few main aspects of the serial killer trope: what creates the killer, what enables the killer, and the serial killer’s logic in their madness. My Sister, the Serial Killer is definitely a story of enabling. While the book does hint at the formation of Ayoola’s psychopathy arising from an physically abusive father who was willing to trade his daughter’s virginity for a good business deal, the meat of the story revolves around the way Korede and society enable Ayoola’s continued violence.
Family Loyalty Enabling the Killer
Throughout the book, Korede is given several opportunities to do “what is right,” with the right thing being turning her psychopathic sister over to the authorities and preventing her from murdering again. This would likely ruin not only Ayoola’s life but also Korede’s and their mother’s. Instead, what we see is Korede choosing her sister’s life over the safety of the men falling into her trap. This brings into sharp contrast ethics vs. morality. In ethics, the life of a single person who has killed several people and will undoubtedly kill more is not worth more than their victim’s lives. However, one form of morality puts the family above all else: familial duty involves doing whatever is necessary to protect the family, even if it means hurting society.
It’s clear that Korede has been taught this kind of loyalty. From the first time she saw Ayoola, thinking she was a doll and a gift, her mother entrusted her with Ayoola’s care, imbuing in her the sense of duty an older sister has to her younger sister. But Korede was unable to protect Ayoola from her father’s wrath. For years the man tormented the entire family, physically and emotionally abusing them until, when punishing Korede for preventing Ayoola from being pimped to a rich business associate, their father suddenly dies.
Who kills the father is up for debate. In the book it is only said that he is beating Korede and then slumps over. Some people think Ayoola did it. Others think Korede did it and Ayoola learned her murderous ways from her big sister’s action. I have a pet theory that the mother, finally roused from her ambien stupor by the selling of her youngest daughter, poisoned him. Whatever happened in that moment, after the father died, Korede was able to protect Ayoola — if only by disposing of bodies as Ayoola kills her boyfriends.
It isn’t a simple “blood is worth more” equation. It is a protectiveness that is rooted in deep guilt for years of being unable to protect Ayoola and unable to protect herself.
At the end of the book, Tade asks what is wrong with Korede. While it’s clear Ayoola has a mental issue, Korede’s enablement is even more sickening to him because Korede does not have the excuse of psychopathy. Instead, Korede has to carry the guilt of not protecting her sister for 14 years of abuse. And to do that, she carries the guilt of each murder that Ayoola cannot feel.
Exploiting the Cracks in Society
I always say that serial killer books are, at their heart, a critique of society. My Sister, the Serial Killer was a critique of several aspects of culture: fawning over beauty, the need to keep up external appearances of perfection, and gender stereotypes. Part of what makes Ayoola confident she’ll get away with her self-defense claims if she’s ever caught is that men all around her are acting shitty. The police harass and extort Korede. Men trade young girls. Everyone is cheating. None of this ever comes into the open because of an unspoken rule to keep the status quo, but Ayoola is sure that if she says a man attacked her, every woman will have enough shitty experiences with men to believe her, and every man will have enough guilt that he’ll also believe her. Although she may be lying about the specific men she kills and the situations around their deaths, she is, in a way, the most honest of all characters — coldly candid about the reality they live in.
Reading the book it feels like any act of honesty could cause all of society to crumble. Ayoola, acting out the tantrum of a hurt toddler, is crushing entire pillars, begging for the honesty that will destroy the world that has caused her so much pain.
Beauty and the Femme Fatal
Ayoola’s beauty and Korede’s plainness is a running theme throughout the book. At the beginning it seems that Korede is jealous of Ayoola who gets anything — and anyone — she wants. Ayoola doesn’t have to learn to cook and clean because her beauty will get her a selection of husbands. She is never punished, and she can get out of anything, including murder. Even the police, when they interrogate her about Femi, are swayed by her charm while brisk towards Korede.
Beauty as a Curse
It seems as if Ayoola is cold-hearted, using her beauty to get what she wants. She dates multiple men at the same time, allowing them to buy her things and pay for her studies and business. At first glance, Ayoola seems like a willing participant in shallow beauty standards. But as the book goes on we begin to see her beauty as a curse. She can’t know whether a man loves her or just finds her beautiful, and violent men have wanted her for her beauty. Even Tade, who Korede swears is different, cannot name one meaningful positive trait about Ayoola when he wants to marry her. Instead he calls her perfect and beautiful.
It is at that moment when Korede’s feelings towards Ayoola begin to shift. Throughout the book she was struggling with whether Ayoola was a bad person — whether those men actually tried to hurt her or not. But when Tade fails to see Ayoola as a person, Korede realizes that Ayoola needs her love and appreciation more than Tade does. And perhaps Ayoola deserves it, too.
Beauty Stealing Purpose
One interesting thing about Ayoola’s beauty is how much it took away from Korede. While Korede had jealousy towards Ayoola’s beauty, her frustration seemed to be rooted deeper than mere sibling rivalry. Going back to Korede’s need to protect Ayoola, we see that Ayoola’s beauty was something that frustrated Korede’s ability to do so. Korede was prepared to protect Ayoola in all the usual ways — preventing her from being teased or taken advantage at school — only to find out that Ayoola’s beauty protected her. No one teased Ayoola. They all wanted her, and as such were overly nice to her. In this way, Ayoola’s beauty took away Korede’s purpose in life.
Korede is angry about Ayoola’s beauty, but not just from jealousy. Instead, she sees that it puts Ayoola in danger more often while taking away any power Korede has to limit that danger. Beauty is something Korede cannot fight or kill. Which leads to her finding another way to protect Ayoola and have purpose in life — being the perfect accomplice to a serial killer.
Beauty As Protection
I’d be remiss to leave out one of the main themes in the book: that beautiful people can get away with more than average or ugly people can get away with. There are plenty of reasons for the police to suspect Ayoola, but as soon as they see her (not only beautiful but also slight), they set aside any suspicion. Her blamelessness extends to all of her actions. She’s able to tell men she doesn’t like their gifts and demand more from them. She’s able to cheat openly on her boyfriends. Her beauty cloaks her in an appearance of innocence that only Korede seems immune to.
When men serial killers are written, they are often given the room to be grotesque. But women killers are usually written as beautiful. Their beauty is their greatest weapon. It lures men, traps their victims, and protects the woman from suspicion. I think this is because men serial killers are allowed to be the antagonist but female serial killers, in books as in society, are expected to always be the protagonist when given a role as strong and bold as a serial killer. (I’d love to read about some unattractive female serial killers… I’m sure the books are out there… and no, old women poisoning people doesn’t count for me).
The Trope Personality Split Into Two Bodies
What I love most about this book is the way Ayoola and Korede seem to act as a single serial killer split into two bodies. They both experienced the same child abuse, so it makes sense that they would develop int serial killers. But Ayoola has the violent, psychopathic tendencies most off-putting in serial killers while Korede takes on the obsessive-compulsive act of planning and cleaning. Reading the two sisters together, you see the full version of a killer fragmented into parts so that they can fight with each other externally. In a way, this best showcases the serial killer’s usually internal struggle — will I kill again? Will I get caught? Feelings of guilt vs. the wilding, need to kill. I think this is one of the most clever ways to crack open the concept of the mental struggle of the serial killer in a way that’s visible, relatable, and visceral to the reader.
The Rise of The Female Serial Killer
I know there were books with female serial killers before My Sister, the Serial Killer. Sharp Objects, for example, came out in 2006. But I think My Sister was a tipping point in serial killer fiction. From 2018 until 2025, it feels like fiction has exploded with female serial killer fiction. Definitely these were not all because of My Sister — many of them had to have been in progress or already written by the time this book came out. It isn’t lost on me that the #MeToo movement also started in 2006 and then hit a flashpoint in 2017. However, most of the serial killer books I come across with a female feature a moral female killer. Most common seems to be the revenge story — in which women can live out their rage through a literary avatar that forsakes society’s rules to enact revenge on those who have hurt her. While those books can be satisfying, I find My Sister adds something more delicate to the conversation of sexual violence and revenge murder.
In My Sister, the Serial Killer, the kills are not always deserved or earned. The women suffer, a misogynistic society prevails, but it is not a revenge story. The women are far from blameless or righteous angels of revenge.nInstead, it showcases the complexity of beauty politics, family, and the dangers of staying silent to uphold social expectations.
