In the summer I decided to get 3 male rats - Delphi, Ruki and Reo (brothers). In their home they all seemed friendly with each other, similar size and well-bonded. Since then obviously they have grown a lot since being babies, but I've noticed that Reo is noticeably smaller than the other two. I am also very concerned that he is being picked on by the other two - I often hear squeaking and 9 times out of 10 it's one of the other two seemingly bullying him? He also seems very shy; again with Delphi and Ruki I seem to have bonded fine, whereas Reo seems very reserved and incredibly unsure of me even after 6months of being here. I have considered splitting them up but I am a full-time student who does not have the facilities or support to do this. Also, I couldn't leave Reo by himself and again it wouldn't be possible for me to go through the bonding stage for the aforementioned reason. I considered neutering, but I've heard this doesn't necessarily change behaviour. I really am at a loss on what to do - I've owned rats for 5 years now but never had an issue like this, and it does make me feel like I've failed them, but the reality is that I love them all so much. Any advice would be greatly appreciated!