How to get cats to like each other?

All my pets seem to become friends with each other on their own. If they're aggressive with each other you can lecture them.

I have a similar problem. I have two male cats, one black and one siamese cat, and they don’t seem to like each other. They haven’t fought yet, but they hiss at each other, and my black cat acts almost like the siamese cat is the «boss».

Another ting, I don’t know if it’s related to the above, but my black cat won’t eat from the bowl even if I call on him to eat. I did make him a homecooked meal, and he ate that without problems. Is he just picky or is he afraid of my other cat?

There is no «be friendly with»-options, and I have castraded both hoping that would help, but no.