When is a cat not worth keeping?

I have two kittens, 4 months old. One is really unpleasant. I don’t mean annoying or loud or hyper chaotic kitten but deep emotional issues that make him very unpleasant to be around. I feed him, give him treats, sit with/near him, cuddle him and try to engage with playing.

He doesn’t like playing and 80% of his behaviour when he isn’t loafing is bullying the other kitten and making her scream, getting jealous over nothing, excessively crying for attention and shitting on the ground, feet away from two large litter boxes I clean daily.

Both cats get equal attention, and I am calm when interrupting aggressive play. I support and comfort him but not excessively, such as when I pet or cuddle him first then move to give attention to the other cat and he goes to my room and cries (daily occurrence).

I get it, and I care about him, but I would appreciate some realistic opinions because regardless of what happens he is objectively a huge pain with minimal upside and I am struggling to connect with him deeply due to his constant crying bullying and pooping despite having a very healthy life and environment.

Looking for balanced responses, I appreciate the livelihood of all animals especially my own but I’m also a human with my own needs.