It’s not really a theme, is it? “Rape”, by itself, is just a subject of the plot — what the story (well, a part of the story) is about. Invincible has many themes, the main one, I’d say, being “perseverance” or “forgiveness”, but “rape”… is not really it.

If anything, a lot of the main themes of the comic are pretty universal and could be understood by all ages. It’s the form through which they are delivered which makes them inaccessible for children, but not the themes itself.