Where telling it from the other side does not work

Every approach has a shape, and a shape means edges. Here are the ones this one has. None of this is false modesty: a parent who buys the wrong book because a website only listed strengths is a parent who does not come back.

It does not work below about seven

The whole mechanism depends on a reader who can hold two things at once: what the narrator is saying, and what is actually happening. That is a real cognitive step and it arrives at different times in different children, roughly around six or seven.

Below it, an unreliable narrator is not ironic, it is just confusing, and the child concludes the book is telling them the demon is right. A five year old needs a straight story with a straight narrator. This is not that.

It cannot teach a specific thing on a schedule

If you need a child to learn one named doctrine by Sunday, this is the wrong tool and a catechism is the right one. Fiction from the other side is deliberately not didactic, which means you do not get to choose what the reader takes from it.

That is the trade. You give up control of the conclusion in exchange for the conclusion being genuinely theirs. If you are not willing to make that trade, no amount of craft in the book will make it do the other job.

Some readers want the earnest version, and that is fine

A percentage of children, including some devout and thoughtful ones, simply do not enjoy irony. They find a narrator they are meant to disagree with irritating rather than funny, and they want a hero they can admire straight.

That preference is not immaturity and it does not need correcting. It needs a different book.

It is easy to do badly

The failure mode of this whole category is a book that flips the perspective as a gimmick in chapter one and then forgets, so the demon narrator spends the back half saying things no demon would say because the author needed the moral delivered. The reader always notices, and the betrayal is worse than never having tried.

It is worth knowing that this is the risk, and worth checking for it in anything else you are recommended, including here.

It asks something of the adult too

A book that does not state its conclusion leaves the conversation open, and some adults find that uncomfortable. The temptation at the end is to close it: to explain what the book meant, in the car, on the way home.

Doing that undoes the whole thing in ninety seconds. If you are not willing to let a child walk away with a reading you did not choose, this approach will frustrate you no matter how good the book is, and that is a limitation of the form rather than a failure of the child.