Interesting

Keep them in separate room but do scent swapping between those rooms. Up to a week.

Then keep the kitten in a cage or similar isolation from the cat but so that they can visually see each other under supervision. Can take a month or so.

Cats can be jealous and territorial (including with you as the owner).

Is it a female or male cat?

引用自 Lindsaayyyyyyyy：

This ♥♥♥♥ won't leave my kitten alone. It literally preys on the thing at every chance it gets. Worst thing is how this cat is a literal ♥♥♥♥♥♥♥♥. Pick it up, it scratches the piss out of you, then looks at you like you've just ripped its tail off. I want to show this ♥♥♥♥ who's boss.

Cats and kittens don't always mix. Sometimes they will be adopted, sometimes tolerated and sometimes attacked. There is nothing you can do other than keep them separated. Kittens shouldn't be let outside until they at least 6 months old, but you can hang on until they are 1 year old if they are really under threat. A good idea is a chicken run. They are protected but it allows the other cats to sus them out. It also gets them used to the outside and the other cats in the area.

A moment of silence for OP.

*bangs drums and blows trumpet*

add a dog