The way the Zoldyck family treats Alluka/Nanika is oddly close to the way some families treats a child a mental illness or a neurodivergence.
Nanika is “something”, something they can’t reach, they can’t control, they can’t understand. It appears suddenly, just like a crisis. It obeys to certain rules, and reccurences. It’s out of control, but it’s not a chaotic force.
But it has a strong destructive potentiel. Nanika can destroy the whole world. For abusive/controling families, a mentally ill and/or neurodivergent child can destroy their world, destroy what they care the most for : their appearance, the illusion of a perfect family, according to social norms they chose to follow.
The roles are reversed. The parents watch over the child for their own safety, not the child’s one.
So they hide them, they limit their activities, their interractions with the outside world. Their needs are denied, but because the illusion must remain, the parents provide for needs the child doesn’t have. For example, by filling a room with dolls and plushies.
The child is deshumanized. They’re just a body who has to act a certain way, say certain words, to please the parent. They’re just the inconvenience, the mental illness, the neurodivergence, the thing.
Then there is this other relative. An uncle, a grandma, a sibling. Who doesn’t see the child as a thing, but see who the child would have been if they were neurotypical.
This is why the scene where Killua asks Nanika to go is so important. He wants to protect his sister from what makes her different - makes her a target for abuse. But Alluka is clear : she can’t do that. She doesn’t want to do that.
“Love as a whole, or no love me at all”, this is what she could have said.
You didn’t escape from abuse if you came from conditional hate to conditional love.
And Killua proves her both he loves them unconditionally.
This is so close to the journey of so many mentally ill and/or neurodivergent kids in abusive/controlling families, it can’t be a coincidence.