Background:
I got two females from a pet shop about 10 months ago. Obviously, they were abused because they were piled up in a fish tank. I could never manage to win their trust to the point where I could touch them. They will spend time in my shirt, or on my lap, take food from my hands but go berserk when you touch them. The one will not hesitate to bite and draw blood. I have accepted the fact that their behavior will probably never change.
Because I felt a bit “unwelcome”, I bought two super friendly males from a breeder (now 4 months old). I kept them separate for some time from the females, had them neutered and successfully introduced to the females. Before introduction, I was in rat heaven because of my awesome relationship with them. They loved being touched and only wanted to be on top of me.
Disaster:
One month after the introduction, I discovered a huge change in the behavior of the two males. They started to run away when I want to pick them up. Two months later disaster struck when one male was diagnosed with cataracts. From here, everything went downhill. Both started running away if they get the idea they are going to be picked up. When I stroke them, they squirm to get away. None of them comes to the gate anymore when I enter the room.
I can understand it from the blind boy that he feels insecure. I have also noticed that every time they came back from vet check-ups they are a bit “wilder”. I live alone and they never see other people – maybe that is why they are skittish when coming back from the vet. Their health is perfect, their diet is balanced and playtime is an average of five hours a day. During the entire night, the cage is open for them to go to their huge potting soil digging box. I want to make it clear, they are not afraid of me – they just hate being touched.
Suspicion:
I suspect this is a classic case of “learned behavior” – if I understand the definition correctly. More and more the males behave exactly like the pet shop females. On a couple of occasions, I have noticed a warmer reception from them when they are alone with me – maybe I just want to see that

Anybody that can help?