How old is Griffin? Is he still a kitten or near kitten age? If so, he may just be wanting to play, and may outgrow it. Or he may fancy himself an alpha male, who wants to let Rosie know he's in charge, and unless she smacks him back a few times, the bullying will persist and it would be a good idea to return him to his foster mom.
I really believe that most cats are happier if they have a feline companion to play and snuggle with. Perhaps if you get another kitty, it should be an older, mellow cat. Could you spend time with another potential companion for Rosie before bringing the cat into your house so you can see the personality? I know that might not be possible for you with everything else that's going on.
Let us know how things go. I know how tough these kinds of decisions are.
I really believe that most cats are happier if they have a feline companion to play and snuggle with. Perhaps if you get another kitty, it should be an older, mellow cat. Could you spend time with another potential companion for Rosie before bringing the cat into your house so you can see the personality? I know that might not be possible for you with everything else that's going on.
Let us know how things go. I know how tough these kinds of decisions are.