This isn't a novel but IMHO the worst example of the "half-breed" character. Anyone remember the TV show Birds of Prey? Damn, it could have been something if it weren't for such autrocious writing.
Huntress, the daughter of Batman and Catwoman (in a whole different universe) was a half breed, or as they often put it - half-meta - because Cats was supposedly Meta powered and Bats was just a trained normal. She was an outcast because she wasn't a normmy like other people and not a full meta like the underground mutant, oops, meta society. The thing that I couldn't figure out is that if all the other supers were full meta, then that would mean that both of their parents had super powers, meaning that there was a whole lot of shakin' going on among the capes. Were the heroes shacking up with the villains like Bats?
Pardon the rant but it turned out to be a lame excuse to give the character an agnst issue. The earlier examples in the thread offer a good view on half breeds but might I suggest looking into todays modern culture, at how we treat folks from mixed nationalities. When we see a child from a black and white couple, do we see the child or do we see the contrasting parents. Sadly, it is how a lot of people perceive the situation. Children of mixed nationalities do feel the heat because of other's prejudice and fears. It can make life awkward and hard, to say the least.
Hope that gives you some fuel to fly with.
Pike