Can you try and help please?

I can't stand bulling myself. I have seen some really bad bullying in my day and I know how you feel that you can't really do anything without being jeopardized yourself. In your case I think you should try to befriend him, let him know that you want to be his friends and want to be his friend for WHO HE IS not just because you feel sorry for him. Try subtle things so that he knows that you are not making fun of him. You say you have classes together, pretend to you didn't catch what the homework was and ask him, or ask him for help on some homework. Once he starts seeing that you have nice intentions invite him again to sit next to you, introduce him to your friends and let him hang out with you guys, people will be less likely to bully him if he is surrounded with friends. If all else fails you should talk to the teachers or principal about it or your parents, tell them what is going on so they can talk to the teachers at school. Well I hope this helps.