Dark books with naive/childlike main characters?

I want to read a dark story that doesn’t pull its punches with a protagonist who isn’t stupid but is actually operating on limited life experience or exposure to the world. Bonus points if MC is strange or odd in a fun way.

I enjoyed the promised Neverland—not a book but the premise was similar in that the main characters were children and had to use their wits to survive despite lack of access to information about the outside world.

Edit: Even more bonus points if the MC is corrupted or goes through an extreme positive or negative character arc. If they do be sure to mention it, I’ll probably want to read the book even more.