We brought home our two male rats, Robin (4 months) and Kiki (7 months), last Sunday. Everything went fine, the boys moved in we were happy to have them, every night we take them out to play, they spend sometime riding around in our housecoats and some time playing on the couch, well last night my son went to get Kiki and he bit him, didn't break the skin. So I sent him in to get Robin and I went to get Kiki, and he bit me, really hard broke the skin and bled for a while. I told him "No Kiki, not nice" and closed the cage and went to clean up. Later I came back to try again and he bit me again, a little one but broke the skin and bled again. I again told him "No, not nice" and closed the cage. When I went in the third time I sat on the floor and spoke to him through the bars in a calm voice. At one point I put my hand up to the bars so he could smell it and he lunged at the bars. When it was time to put Robin back I noticed that they seemed to be arguing, standing up and "boxing." I also noticed Kiki standing on top of Robin's head and Robin is usually the dominant one. Kiki also pushed Robin out of the way a couple of times. I am just wondering how I should proceed tonight? I'm a little wary of getting bitten again but I'd really like for him to come out and play, I haven't had any problems with him since he came home and he usually likes to be out. The cage they are in has two doors and we tend to use one door both for feeding them and for taking them out of the cage, should I try taking them out only using the other door? Should I just open the cage and let Kiki come out on his own? Any advise would be helpful.