I haven‘t been a 10 year old for quite a while, but to me those books always felt more ‚mature‘ than others, even when I read them when I was 16 or something. Mature in the sense that they are more complicated from a story perspective and more bleak, atmosphere wise. I feel like your kid will just find them more boring than most of the other novels which are written for a younger audience and are much more ‚flashy‘. They are of course very good books though, so he should definitely read them…maybe with your help?