Ive only been bite hard by 2 of my rats, both times were accidents, 2 of my rats got in a few, numerous times and I had nothing to do other then to hold my breath and shove my hand in (stupid idea) fitrst, abel bit my forearm, didnt really hurt but he took a huge piece out, you could see down to the fat. Second time, my boy Octavian grabbed a hold of my pinky finger right over the knuckle and bit down as hard as he could.. ITS HURT LIKE HELL!.. I felt it go deep and then all of a sudden I felt a crunch, he hit the bone and omg if you think normal bites are painful, feel that!!!! I had to pry him off. My pinky was huge for about a week, its been months and months and the knuckle still hurts if I move it certain ways, i'm pretty sure he fractured it.