hi
i got a rat about 6 months ago and i love him to bits. sometimes when i stick my finger through the cage he goes straight to my fingers and tries to nibble on them because i feed him treats through the bars but he doesnt nibble hard and you can hardly feel it so don't be scared. rats are intelligent animals and hardly ever bite on purpose. they probably think you are feeding them food as their eyesight is not too good. just try to feed them treats in their cage and let them get used to you and when you can, handle them as much as possible and they will get used to you and give you lots of love and affection. good luck