"fictional children"

If I've said this once, I've said it a thousand times. If it's porn involving someone who "doesn't exist" (i.e. a fictional character), then it is generally protected by the First Amendment (there is also no scientific basis for prohibitions as I establish there, * also applies).

Typically, the law here follows the doctrine of the "fruit of the poisonous tree", so one theory for prohibiting "actual child porn" involves an actual minor actually being abused to produce it.

There is also a privacy like theory where if something deliberately looks like an actual minor, then that is grounds for someone being held personally liable.

The doctrine of the "fruit of the poisonous fruit" also applies to searches under the Fourth Amendment where if evidence originates from an illegal search then the evidence itself is considered tainted.

Also, keep in mind, that concepts like "child-like" can be notoriously fuzzy, and it's not in anyone's best interests for such a subjective call to be made.

* https://qoto.org/@olives/111888946356326887
QT: https://qoto.org/@olives/111516011246609826