I socialized my little ladies by using the sweatshirt approach a few times. I'd also take them out individually and put one of them in a snuggle pouch, then I'd go downstairs and sit with whoever I had and watch TV. I took them out individually sometimes, only because I wanted them to be able to bond with me, not just each other (even though they were already familiar with each other because they had lived in the same aquarium at the petstore with some other babies). Another thing that I did was I would lay a beach towel down in the bath tub, and Iâd stick a pillow in there up against one end of the tub. Then Iâd sit in the tub all comfy with my pillow, and Iâd let my girls run around and get used to me. Iâd pet them or pick them up a few times, and sometimes Iâd give them treats. While I was sitting in the tub I could do homework or read or whatever as I let them get used to me. It worked pretty well, and within a week or so, theyâd come running up to the front of the cage when I came in the room, begging for me to cuddle them.
Also: Is your rat alone? If he is, like jorats said, it might help if you got him a buddy to help him feel a little safer.