I've had pet rats as well and while they're incredibly smart and gentle, it did take a while for each of the two older females to get used to being handled, and being handled specifically by me. I did get bitten a few times while learning the difference between how books and websites say to handle a rat and how to really safely and comfortably handle one!
From that, I can say with complete assurance that if a rat bites a baby enough to leave 200 bite marks, they're going to be HOWLING. I admit to saying a few not so nice things myself and having tears brought to my eyes a time or two, and I was about 22 when I had them.
Did I mention I never got nailed more than once at a time?