help me please!

Question
i got my first rat (female)like around the last week of february or first week of march (of 2007) named Graves and shes really friendly with me. when i got my second rat(also female) serendipity, she was scared and graves used to bite her all the time. so i seperated them. they live in their own cages. i think about putting them together, but the last time i tried (it was about 3 months ago-serendipity is now twice the size of Graves) serendipity now bites graves or ends up peeing on her (while walking over her head). what should i do? do they do this only for a short time? by the way they are about 9 months or so now if that makes it easier.

Answer
You need to take a step back and read about rat behavior and introductions. I answer questions like this all the time; and several of my answers will give you some ideas; otherwise I do very very much recommend you look into introducing two rats on the web --- as there's a ton of information out there and AllExperts isn't nearly big enough to explain it all! They could learn to get along and live happily together, it just needs to be done right.