
They're playing. I'll give you more body language to look for, but this sounds JUST like our Ming Loy. She is ALWAYS the instigator - but as soon as someone responds, she acts like they're killing her and she's dying. We used to intervene - and now we know... she's like that little kid that puts her foot out to trip someone, immediately pulls it back and looks all innocent. The person tripped gets up and shoves the kid that tripped him - and the kid that did the tripping starts screaming her head off.

And no one got hurt or was in any real danger of being hurt.
Watch Mooking playing, especially when you use a wand toy with him. Does his tail ever puff up - look like a huge bottle brush? Does he hiss? Because when most of our kitties get really involved in play, they'll hiss at the toys, and/or their tails will bush up.

So it's a normal part of play - even though hissing is used to communicate a warning as well, and the "tail bush" is a defensive mechanism that makes them look bigger when involved in a confrontation. They also happen naturally during play.

What would indicate a serious battle would be
1) Ears FLAT BACK - it makes the cat look very menacing. It's not just ears down - that they do to protect them from feet/claws/mouths. No, this is flat and turned to the back;
2) the back ridged - it is very easily identifiable, as it looks like your cat has a mohawk all of a sudden.

If you have to ask "is that a ridged back?" it isn't.
The tails can be confusing, because during play they can be down and twitching. But if they are "tails up" then there is just no DOUBT it is play. A "tail up" kitty is a friendly kitty, always.
But sometimes they can get a little rough during play. We usually "interfere" just by making a loud noise, like clapping, or just yelling "HEY!" you two, calm down! Or stomping really loudly on the floor as we start heading toward them.
If they're really in a fight, you need to throw something over them to stop it, because you WILL get hurt if you physically try to break it up.
So I'm pretty sure what you're dealing with is play that's just getting a little... over-exuberant.
