Just a thought, I reckon that Harry's spent most of his time around adults, not kids, given who his father is and who his father's associates are. I'd expect him to talk a lot mroe adult than most 11-year-olds. Not sure I should talk, though, by that age my father had gotten me hooked on sf, and not just the "young adult" series, and I was enjoying a quite adult environment, that way, myself.