I adopted a new kitten approximately 4 months ago; Mister Black. He was an older kitten, and has had persistent diarrhea since I brought him home. I don’t need advice in this regard - all options are being explored with a vet and I’ve spent many hours trawling the web for potential solutions. The vet’s opinion is that he’s all-around healthy, minus the diarrhea.

He’s got definite crackhead energy, and receives plenty of play to wear him out to the point of panting. Still, he will occasionally go directly from cuddling to biting or clawing my legs. I’m starting to suspect his original home may have played with him using their hands. I respond with yelps, removing myself from the room or re-directing to a toy, but it doesn’t have any lasting effect.

I already had another cat, Mister White, who’s frankly spoiled me with his good manners and gentle spirit. I’ve had him since he was a tiny kitten just ready to leave mama, and he’s a year older than Black. The two of them can hang out supervised, but White distrusts Black after he’s tried to roughhouse one too many times. They were introduced slowly with scent swapping. Their playstyles are completely different, so I haven’t managed to find a way to play with them together (Black enjoys adrenaline and muscle play, White enjoys stalking and chases with no contact). They can eat together just fine, although Black has to be actively discouraged from eating White’s food.

Black is being castrated next month, which I’m hoping will help alleviate some of his issues (It’s taken this long due to waiting for his medical issues to resolve). But I’m concerned that it might not - in which case, where do I go from here?

tl;dr: kitten is Satan and old cat is Jesus, what do?

ETA: It’s worth adding that I have 18 years of experience with cat ownership with multiple different cats, and I haven’t experienced anything like this before.

  • Black is being castrated next month, which I’m hoping will help alleviate some of his issues (It’s taken this long due to waiting for his medical issues to resolve).

    this here i think is your answer. Just hold out and wait for the cut to be done and for things to settle.

  • The castration may help to moderate the behavior, but to hedge bets:

    Is there a treat that Mr. Black likes but Mr. White does not, and possibly vice versa? And do they each have their own call sound or other audible mark you use to get attention from them? There might be an opportunity to begin working on marker training better play habits out of Mr. Black even before his surgery.

    • Sorry for the late response! Black doesn’t get treats currently, as I’m not sure what his stomach can tolerate. I praise with intonation and their name. Unfortunately I haven’t seen any positive play; Black is probably a reincarnated Wrestlemania fighter.

      • No worries! Food sensitivities can make this harder, but not impossible. What we’re looking for is a way to reward Mr. Black for disengaging from Mr. White - this can be treats, play, physical affection, really anything that Mr. Black enjoys (besides being a dick to Mr. White). The set up:

        Mr White exists, Mr Black is doing the behavior before it escalates to the problem behavior. (If this change happens too quickly to interrupt, pick an intervention point based on their behavior pattern, just earlier in the cycle.)

        You call/get attention from Mr Black, and reward this change in focus with some play or scritches or whathaveyou.

        Mr Black is allowed to go do his own thing again. Repeat as necessary.

        This intervention helps to teach Mr. Black that at a certain point in his excitement building, it’s far better to go get something awesome from you at that point, because he’ll get to go do whatever after he checks in with you. It will take patience and repetition, but it is doable (we had to train a pair of older brothers when one’s health started to decline). The act of checking in with you allows Mr White to relocate if they want to, and “resets” the excitement level Mr Black is experiencing.

  • I had two cats from the same litter who had opposite personalities, just like your two. They were both fixed as kittens. The male was very aggressive with play and dominant, he would try to hog everything. The female was very calm and gentle, though she would fight back if the male was being a brat. I had to feed them in separate rooms, also play with them separately. They occasionally played together, but not much, even as adults. I used a spray bottle to deter bad behavior like biting. I got a big glove to use when rough playing with the male. They eventually worked out a heirarchy amongst themselves for cuddles, but they were always very different personalities. The male calmed down as he got older, but it took time.

    Point being, yours may never gel and get along to the point of you being able to have them do everything together, and that’s ok. But I think your intuition is right, he will calm down as he gets older and is fixed.