I'm having trouble finding my 12 yo (doesn't turn 13 until the end of March) 8th grade highly advanced reader son books that challenge his reading ability without containing content (or language) I don't feel he is ready for yet.

He's currently reading books off the High School Battle of the Books list but some of those also have questionable (in my eyes) language and content.

He read the Harry Potter series back when he was seven and tends to like books within that genre. He picked up Scythe at the library (I knew nothing about it at the time) and had it read within the first day. Got him the sequel Thunderhead and he had 120 pages of it read within the first 75 minutes. I then started reading about it's content and found it a bit more mature than I was expecting.

So now I'm turning to you for any recommendations you might have for books that are challenging but age appropriate!

Thank you!