I think that’s a great age to read the Percy Jackson series. I never finished it, but I found the books I did read enjoyable.

Where the red Fern grows, Maus, Holes, series of unfortunate events, I think Bea Wolf looks good too but I haven’t had a chance to read it yet. Edit, Maus and Bea Wolf are both graphic novels so maybe not what you’re looking for. But Maus should definitely be required reading, especially now.

I used to read the Hardy Boys, Nancy Drew, Chronicles of Narnia, Artemis Fowl (earlier boxcar children).

I never really got into them, but Terry Pratchett’s Discworld books are really popular. My friends around then liked Animorphs.

(It’s hard for me to judge reading level super well because I was always pretty ahead of my age group, so take it with a grain of salt.)

Another suggestion is find a local library and just wander the kids section with them. They should have stuff managed by approximate age level and you should be able to find stuff that way.

Beverly Cleary’s books, Roald Dahl’s books, Piers Anthony’s books, Stuart Little, the Redwall series, etc. I don’t remember what age I picked up Ray Bradbury’s books, but The Illustrated Man might be a place to start too.

Maybe some Borges too?

My kids have participated in the Battle of the Books at school, and I read some of them with them… Some amazing book quality that I wish I had as a kid! They pick really good ones. https://www.oregonbattleofthebooks.org/2024-2025-titles/

My little reader enjoyed “The Wizards of Once” by Cressida Cowell.

I think I was about 12 when I first read The Lord of the Rings. So I suggest giving him The Hobbit and seeing how he likes it.