Do pet rats bond for life or can they be separated and introduced to new rats?

[Scooby Dooby Doooo]

I have 2 older ratties and I'm thinking about getting rid of one of them because we have tried everything to get her to stop biting and drawing blood and nothing has worked. She is wild and psychotic. We adopted them when they were over a year old and have had them for 6 months. As far as I know, the adoption place got them together so they have always been together.

What would the consequences be, if any, for removing one of them from the other? And would replacing her with a new younger rattie help the remaining rat cope or make the problem worse?

 

[Ratty Rockstar]

I'm sorry to hear about the problems you are having with the one rat.. It sometimes happens. Chances are, she was not always handled with love and care her whole life.
I urge you to try a few more things, before giving up on her.. For the simple fact that not many else will want her. Below is an article I've found on trust training. I'd like to think it'll help, but she seems to have some major aggression problems.. I still urge you to give it a try if you haven't before.
Trust training: http://www.ratfanclub.org/trust.html

If the one rat shows no signs of aggression, that introducing a new cagemate may go over quite well. Keep in mind though, that yes, she is bonded to the one. She will know the difference. And she may mope for a bit. Sometimes they do. Sometimes they don't. I have read articles that state that new fuzzlets sometimes bring out the maternal instincts in some older females.
Heres a few articles for you if you go through with it, and how to properly introduce them..
http://www.ratfanclub.org/newrat.html
http://www.suite101.com/article.cfm/pet_rats/24945
http://www.rmca.org/Resources/aintro.txt

Hope something here helps you out.