Okay, so I guess I should start from the beginning... 2 years ago, we bought 4 male dwarf hamsters from the same litter. However, after about 6 months we found out that one of them was female when she had a litter of 7 babies. We gave 6 away to separate good homes of people we knew and trusted, and kept 1 for ourselves, who we named 'Fish'. However, Fish is the only surviving hamster from the litter, we can only put this down to the fact that they were a litter of inbreeds, meaning it is possible they had birth defects or something.
Fish was great at being handled from the first time we held him - which is why we chose to keep him. We handled him regularly and treated him well, but at about one year old my sister was just holding him as normal when he screamed and viciously bit her, drawing blood. We put him back in his cage, and tried to hold him again the next day but he bit us again. After about a week, we gave up. About 6 months ago, we tried holding him again, starting with gloves and hoping to work gradually until we could hold him bare handed, but he just kept squeaking and biting at the glove.
My theory is that he is in some sort of pain, so that holding him causes him distress, but he is fine when in his cage so that doesn't make complete sense. The only other thing about him that seems abnormal is kind of hard to explain and may just be normal for roborovski dwarves as I havent had one in a hile so can't really compare. When he walks around he... 'waddles' thats the only way I can describe it. He wobbles from left to right as he walks, maybe im just being paranoid but it doesnt look very normal. Also, his rear end seems very tucked in, rather than sticking straight out backwards as my syrian's does, his tail points downwards and his bum seems curled in I dont know, maybe its normal :S just tell me what you think!!
Also, whether you think its too late for me to be able to train him not to bite, and how to train him if its not to late!!!