I keep thinking about how cuckoos are so much bigger than the birds whose nests they lay their eggs in. I can't recall where I would have read this, but in some part that has to be about the bird parents' instinct to feed the strongest baby the most. Like even if they could suspect that there is something off about this one singular baby, who eats as much as a whole nest of babies, and is mysteriously the only one in the nest, that is still a big, strong, beautiful baby. Having some clouded contemplations of "if feeding my beautiful huge baby is wrong, I don't want to be right", immediately pushed down to whatever they have for a birdy little subconsciousness.
What if changelings work the same way? Needing so much more care than a normal child, but being so compelling that doting on this little creature is impossible to resist? A child that is so much more sweet and perfect than any human child ever could be, easily possessing every human virtue - so thoughtful and kind, polite and well-mannered, that you hardly even notice that three other kids went missing at some point.
Pushing down suspicions that this impossibly perfect child isn't human, that it isn't yours, because you don't want to think about that. Refusing to contemplate that your sweet beautiful baby is going to do the same thing to someone else as their parents did to you. Someone else's children will be gone, replaced by just one, a perfect one, too perfect to be human. But you don't think about things like that because that's your baby.
