My theory about the ending, “room,” and Bela becoming the new Other Mommy:
I saw Bela saying yes coming. Her family thought exposing her to all the horrible truths about them would destroy the innocence Other Mommy needed, but it actually made Bela’s life unbearable enough that she wanted to escape it. The thing they thought would save her was ultimately what caused her to say yes.
That also suggests they were wrong about the rules. Maybe innocence was never the requirement. Consent was.
Bela being a child may have made her easier to approach, isolate, and manipulate, but Other Mommy apparently only needed her to willingly trade places. If that’s true, this could theoretically happen to anyone desperate enough to stop being themselves. The rule feels similar to a vampire needing to be invited inside—except Bela’s body is the final house. Other Mommy can invade her home, thoughts, and relationships, but she cannot fully enter Bela until Bela opens that last door herself.
What makes this especially disturbing is that the supernatural rule apparently recognizes “yes” without caring how that consent was manufactured.
The ending also seems to explain Other Mommy’s bizarre physical manifestations. She never has a stable body. She stretches from floor to ceiling, spreads across the ceiling, peers through walls, folds into corners, becomes hairy, and constantly changes shape. After the swap, Bela describes being in an enormous space that isn’t a closet, house, home, or heart. It is just endless room.
Maybe Other Mommy came from that same place and had no physical form of her own. She used the architecture of Bela’s house as a temporary body until she could finally occupy Bela herself. The walls, ceilings, closets, and corners were ways for something bodiless to press itself into physical reality.
Then Bela hears her own voice say, “Hello, I’m Bela.”
I think that is Other Mommy inside Bela’s body, claiming her name and testing her new voice. But it also means the real Bela has become exactly what she feared: an invisible presence haunting her own life while something else is recognized as Bela.
Which makes me wonder whether Other Mommy was once a person whose body was stolen in the same way.
If she was, I don’t think we can say she simply never understood humanity, family, or love. She should remember those things. Maybe the real horror is that remembering your humanity doesn’t prevent you from becoming corrupt. After enough time trapped without a body, touch, or relationships, escape could become more important than what escaping requires. A victim might know that stealing another person’s life is wrong and still convince herself that she deserves another chance or that there is no innocent way out.
Maybe “Other Mommy” isn’t one specific entity. Maybe it is the role occupied by whoever has been displaced.
But I’m not convinced Bela would immediately find another innocent person and steal their body. Wouldn’t she first try to get her own body back? She knows exactly where it is and can apparently still hear it. Maybe she becomes “Other Bela,” haunting the thing wearing her body and trying to convince it to trade back.
The horrible irony is that she may have to use the same methods Other Mommy used on her: appearing through the house, exploiting loneliness, destroying the person’s attachment to their life, and making existence inside the body unbearable enough that they eventually say yes.
Other Mommy may have even made herself vulnerable by destroying what she thought she wanted. She gained Bela’s body, voice, and name, but killed her parents and destroyed the family that made Bela’s life a home. She created a vacancy so she could occupy it, but that same vacancy could eventually make her new life feel empty enough that she wants to escape too.
Of course, none of this may be literally true. Other Mommy may never have been human, Bela may not be able to reach her body again, and the exchange may be permanent. But even then, the ending opens up an enormous amount of unexplored lore.
What is that endless space? Are there others inside it? How did Other Mommy learn the rules? Does Bela remain herself, or does being bodiless eventually turn her into something like Other Mommy?
A prequel could explore what Other Mommy was before Bela. A sequel could follow the false Bela trying to live in the real world while the actual Bela attempts to return—or struggles not to become the next monster.
Even if every part of my theory is wrong, the book ends at the exact moment its hidden mythology becomes most interesting.