i second persepolis, i recommend wormwood (though you might have to skim for appropraiteness depending on which one he gets? i've only read one) and here's a list of award winning graphic novels (http://en.wikipedia.org/wiki/List_of_award-winning_graphic_novels). if you, your boy, and his school don't mind pirating too badly, i have a few of the batman ones and most of the alan moore's i can megaupload for you.