One cat doesn't understand the other is just play-fighting

Question

My girlfriend and I have two three-year-old cats: Napoleon (male) and Josefine (female). They are siblings from the same litter. I have been studying abroad for the last 9 months, so currently my girlfriend's the one taking care of them.

The two cats get along just fine for the vast majority of the day. They eat together, the female frequently bathes the male (though baths usually become a small fight for some reason, and she really doesn't like it when he tries to bathe her), and my girlfriend sends me pictures (and videos) of the cats sleeping cuddling together in the most adorable ways at least once a week.

However, whenever the two play together, Napoleon seems to have a hard time understanding the boundaries of acceptable behavior and takes things a bit too far.

It doesn't help that Napoleon is significantly larger (1 kg = 2 lb heavier even though they're the same age) than Josefine, and that she sometimes honestly seems to ask for it.

As a representative example, please watch this 45-second video. Josefine waits to ambush Napoleon as he leaves the bathroom (where we keep their sandbox) and gives him a light tap on the head (I interpret this as a play-ambush). He gets seemingly startled and then the situation momentarily escalates (but not severely), followed by Josefine becoming slightly submissive (hunching down) and letting out long, trembling meows as both seemingly vie for an opportunity to strike. Napoleon then lets out some meows of his own and Josefine becomes very submissive, lying down.

The video ends there, and my girlfriend says that's when she interrupted the fight by calling their attention. In similar situations when she hasn't stopped them (she usually lets them solve things out for themselves), Napoleon will go for a bite or something of the sort, Josefine will bat him away and run away, at which point Napoleon will sometimes give chase. If he does, the fight continues with more jabs and some biting. Nails always remain sheathed and the bites don't seem to be meant to injure (no one's ever come out bleeding, shall we say).

Sometimes we just see the chase and don't see the instigating incident (or whether there was one), but Josefine seems to be the usual initial instigator. Other times the cats play "tag", running around the house with no issue.

Once the fights are over, the cats don't seem to avoid each other or anything indicating lasting animosity. That being said, one time (and only one time that we're aware of) Napoleon did end up with a tuft of Josefine's hair in his mouth.

Since neither cat seems very affected by the fights, my girlfriend usually doesn't interrupt them. That being said, we'd rather stop this behavior or at least understand it better.

Is this actually just normal play-fighting (and the time Napoleon got a mouthful of hair was then just a one-off accident/escalation) to be shrugged off? Is our interpretation of Josefine's behavior incorrect, and she isn't play-fighting at all? Or, if we are correct in our diagnosis that Napoleon simply doesn't know how to play-fight, is there some way to teach him to turn it down a notch?

For some further context into our cats' recent history and how their behaviors changed (quite significantly) after I left to study, please see this other question I asked 7 months ago. This type of fighting also only started after I left, so that context might be relevant. (Also note that the issue raised in that question has passed)

Answer 1

As a representative example, please watch this 45-second video.

From my reading of this video:

J is playing. N is genuinely annoyed. J makes herself small to goad N into playing with her. It's not so much a matter of submission as more giving N the high ground so he's more inclined to actually pounce.
N, on the other hand, is making himself large to show that he is unhappy with her ambushing him.

This is a clear miscommunication. J reads N's behavior as being goaded into playing, when in fact he is scolding her for ambushing him. N reads J's behavior as admitting she made a mistake, when in fact she is trying to urge him to play together.

Josefine will bat him away and run away, at which point Napoleon will sometimes give chase. If he does, the fight continues with more jabs and some biting. Nails always remain sheathed and the bites don't seem to be meant to injure (no one's ever come out bleeding, shall we say).

Their actions here are consistent with a cat that actually chooses to join in the playing.

We see this happen all the time in our house. The youngest of the three, incessantly playful, used to pounce on his sisters to start a play session, but they did not like that (and he would be driven out of the room). After a while, the youngling learned that instead of pouncing, he instead made himself look weak and thus lured his sisters into playing with him. If they responded, that means they wanted to play. If they didn't, then they don't want to play but at least he didn't upset them.

Given that there are no nails or hard bites, how sure are you that Napoleon is fighting with her and not play fighting?

This may be on a cat-by-cat basis, but we've noticed that it's only a fight when someone hisses. Anything before that is fair game. We can gauge this by the cats' reaction when we call out. If both of them stay there, it was a play session. If one of them makes a hasty retreat, they were an unwilling participant.

If N genuinely can't handle J's playfulness, you should provide J with more toys or playsessions with you so she can get her energy out. But otherwise, just letting them solve it themselves is the better solution as long as no one gets hurt or aggravated.