Should my rat Ryu have a friend :)?

If your rat is perfectly happy with being alone and with you then, no. But if he's sort of lonely then yes. BUT! bake sure it's a LADY friend since males always want dominance. Two months is okay but if it was younger it would be better since he'd think she was part of his family! Some advice would to be watch and make sure they aren't hurting each other. If they do, then you should separate. It's a good idea also to have a little 'PLAY DATE' first to make sure they will like each other.