I am know expert to all of this but maybe a little seperation untill he bulks up and gets more confident might do the job. I`ve got a hob and jill together at the moment brother and sister and i thought i was going to have to seperate them. He`s twice as big as her and likes to try and boss her about but once she`s had enough she kicks his ass. W hen he or she comes into season then obviously i will heve to seperate them but untill then they r fine together. Also i suppose it`s just the pecking order . Hope it all goes well .