In the past few days that I've had the ratty boys, they've really seemed to calm down and adapt to their new home. It's wonderful observing them while they explore and play in the living area, darting behind furniture, climbing into boxes, figuring out what they can and cannot fit into. They try to get on, in, under, and behind everything in the room.
Their curiosity and intelligence is shocking actually. Watching as they interact with Bob, their boldness and inquisitive nature leaves him completely confused and uncertain how to react. Homer is more assertive and, for the most part, seems unconcerned with Bob's playful swats. Undeterred, he walks right up to the cat and tries to climb on his back. lol
Grizzle, on the other hand, seems naturally more nervous and frightens rather easily. He and Bob are still trying to reach an understanding. I moved their makeshift fence to another part of the room to create a small play area where they are free to come and go, serving as a barrier for them to interact with Bob without the play getting too rough.
As for introducing the cat to new rats... I wouldn't have tried this with an older cat. Luckily, Bob is only 18-19 weeks old and hasn't reached sexual maturity yet (not too hormonally-crazy yet, in other words). He's doing pretty well so far and I'm very proud of his ability to listen (at times) when his play is getting out of hand. At times when he can't control his excitement and let the rats play without chasing them around, I set him in time-out for a few minutes in the bathroom. If that doesn't work, he goes into the bedroom for a nap while the rats are out of the cage running around.
I worry that Bob may be jealous of the new family members, so I'm careful to give him plenty of attention and petting while all of us are playing together. Keeping his toys nearby also helps since I can stick a toy mouse in his mouth or throw it across the room to distract him for a little while.
I also make sure to feed Bob before all others so that he understands he's my "numero uno".
Since Homer can still slide through the bars of his cage, there's no way to limit his interaction with Bob. Thankfully those two get along pretty well. In fact, I'd say Bob is more uneasy around Homer than the other way around.
You don't see something like this everyday!