There are marble varieties too that might explain the spots- my angel escapes just fine but he does try to "kiss" her sometimes..lol I don't know anything about discus but as he gets bigger he will chase them for sure. When they are little they usually are not aggressive. Just keep an eye on him and have a place to seperate him or any sick or injured fish so he doesn't get an easy opportunity and when he gets aggressive trade him for another baby!