Other Mommy villains explained: Jessica Chastain plays both the demon and the mother it impersonates

Rob Savage's film, adapted from Josh Malerman's 2024 novel Incidents Around the House, follows Bela, a young girl played by Arabella Olivia Clark, and the thing that visits her at night. Jessica Chastain plays Bela's mother, Ursula, and she also plays Other Mommy, the creature that looks like Ursula and keeps asking Bela to let it into her heart.

What Other Mommy actually is

A demon that has never been alive and wants to be. The film says so before anything else happens, in an opening title card: "Humans have one thing that demons don't – being alive."

Its rules are simple, and the film sticks to them:

• It needs permission — it can't take Bela by force. She has to agree to let it into her heart.
• Agreeing is fatal — letting it in means Bela dies and the creature takes her place in her body.
• It works on trust, not strength — it plays friend, plays mother and leans on whatever loneliness and tension it can find in the house.

That last rule is why the creature spends so much time on the family's secrets. A child who feels lied to is easier to talk into something.

Why it wears Ursula's face

Because it puts Bela at ease. Savage has been clear that the mother isn't what the creature really looks like.

"Ursula, Bela's mother, is not the form that Other Mommy naturally takes," Savage told Phantasmag.

Chastain built the performance around the strain of keeping that disguise on. What helped her most, she told Extra, was the idea that "it's painful for Other Mommy. That she's in pain." The disguise slips in small ways: the face sags, the feet leave the floor, the body folds the wrong way under a table in the shot that made the first trailer infamous.

In Malerman's novel, the creature doesn't bother with a convincing disguise. It is closer to a bird, with eyes that drift around its head and a smell that makes people cough.

The other faces it wears

Ursula is the main disguise, not the only one:

• Ursula — the default, and the face that gets it closest to Bela.
• The babysitter — it borrows the sitter's form as the haunting escalates.
• Bela — in the final confrontation, it comes to her wearing her own face and asks for a hug.

The novel gives it a longer list: the voice of Bela's friend Deb, her teenage babysitter Kelvin and, finally, her grandmother Ruth, whose body it leaves in a closet.

Don't miss: Other Mommy book vs movie: every major change from Malerman's Incidents Around the House

Is Ursula a villain too?

The only other villains in the film are the ghost hunters Bela's grandmother hires, who care more about studying the creature than stopping it and pay for it when their séance actually works. The more interesting question is Ursula.

She isn't a monster, but the film doesn't let her off. She's having an affair with Frank, a family friend played by Arian Moayed, and she has been hiding something bigger: when she met Russ, Jay Duplass's character, she was married to someone else and already pregnant. Russ isn't Bela's biological father, and he has always known.

The creature drags that out of her in the basement, where Bela can hear, along with a second confession: Ursula never wanted to be a mother. Chastain has made no secret that this is the part of the film she wanted to push on. She told Porter she likes challenging the idea that "women are supposed to be grateful for everything — that includes motherhood."

The demon wears Ursula's face to get close to Bela. By the end, it has also made Ursula say out loud the thing she'd been hiding behind that face.

The ending leaves her there. Bela defeats the creature by accepting that her parents are flawed, and the last scene has her laughing with Russ while Ursula watches, visibly unhappy. The haunting is over. Ursula's marriage and her feelings about motherhood are exactly where they were.

Previously we wrote: Yellowjackets has one season left to live up to season 1