Late to the party: The "Animorphs" series were what finally got him interested again. Kid heroes (boys and girls), crime fighting, low-level sci-fi. I read 'em too, just because, and they weren't bad. A couple were actually kinda good.

All three of our kids enjoyed the series, and Milady and I read them, too, "just to see what they were reading," and because, yes, there was some good stuff.

Avoid the final book, though. Looks like the author either resented being told to end the series, came to hate the characters, or just gave up on it. In any case, we all wished we'd not read it. YMMV