Aggresive behavior or play?

Hi All. I'm new here to these forums. My story is this. My husband and I rescued a very small sick kitten last summer from the middle of the road. Over the past months he has grown into a beautiful, loving, playful, healthy boy. The perfect cat basically... maybe a bit on the skittish side but otherwise wonderful. My husband and I both work very long hours and decided to get Mattingly a playmate since so much of what we have read said that cats often do better with a friend. Our vet said a new cat we get should be his age or younger, and that a kitten should be fine. So we adopted a kitten from a shelter (still unnamed). She is very playful but quickly learning that we don't tolerate biting and clawing of hands in this family. We have been following all the introduction protocol we have found, and the two of them are moving it along quite quickly... crying for each other when they are apart. We know that when they are in the room together, supervised, that there might be some growling and hissing. But how do you know when it's rough play and when it might be too much? I know a knock-out drag-down fight when I see one, but Mattingly is bigger than our little one obviously, so how do we know if he's hurting her? She'll hiss and growl to tell him to stop, then runs away, turns around, presents her belly, and the whole thing goes on again. We are worried about two things. One, is he being to rough with her? Two, is this going to affect their future relationship? Any advice on this? Do we break it up or allow it to continue?

One last thing, is that tonight she got ahold of his favorite toy twice. We've been keeping that from her (as well as keeping her from his favorite hiding place) so that he knows some comforts still are just for him. But tonight when she got ahold of it, she growled and wouldn't let go. When my husband picked it up to take it out of her mouth, she growled at him too. I've never seen anything like this in a cat (dog yes, but not a cat). What do we do about this? Thanks for any advice you have!

Welcome!

How long have you had the new kitten?

We're with our fourth cat (whitey) and after 7 weeks are still suffering some hard-core rough style playing.

Sounds a like they're both after the role of the dominate one. Cats do growl, even at people, so be a little cautious if either do growl at you (but let them know that they're not suppose to do that).
Just keep supervising their playing for a couple of more weeks. Since its only between 2 cats they'll sort it out shortly. You may see them go back at it every so often, but its just the joy of being a cat and territorial!

It sounds pretty normal to me. If she is asking for more then she is not getting hurt. Mine still growl and hiss when they are playing (or sometimes when one annoys another) but as you say you can usually tell when it is an out and out fight and you have to intervene. If it does get too much I would take one (the aggressor if you know which one!) and give him/her some calm time out in a room on its own for 15 minutes, then usually all is well.

Thanks for the encouragement! Last night we started playing with them using toys, so the attention wouldn't be just on each other and it's starting to work. We've also started gently breaking them up when the play seems to get too rough for her. Our older boy, Mattingly is so smart, and is already learning the boudaries. Sometimes he gets a little overzealous, but he is now backing off much more quickly when she growls at him and is getting gentler. Our trick is to not be too harsh with him because he is such a sensitive guy and prone to being skittish. I think it's going to work out just fine. Anyway, I'm glad I found these forums!