gender confusion & neutering?

Blackie is neutered.

You might recall that he used to groom Sparky and Sparky would try to nurse from him. That hasn't happened in a while, so I guess it stopped naturally, but it was cute and I kind of miss it.

Fred is not neutered. Every now and then I catch him on top of Blackie. Blackie does NOT appreciate this. I usually separate them, and I tell Fred that he can't have kittens w/Blackie because they are both boys. The only other time I have seen this kind of behavior this consistently was when someone I knew had a breeding pair of Persians (the tom would never leave the poor queen alone, every time she sat still he was on her).

So I'm wondering, is Fred confused because Blackie, being fixed, doesn't smell like a male cat?

This is dominance behavior. Fred is showing his dominance over Blackie.

Also....it may be a sign that it is time to get Fred neutered. How old is he?

It's actually past time for Fred to be neutered, I simply haven't the money to do it until I am working and my divorce is final. Hopefully I will be able to take care of that sometime in the next month, maybe a little longer.

I didn't think of it as a dominance behavior. I thought maybe the neutering messed up the hormonal signals to the other cats. But since Fred is the most aggressive of my cats, it makes sense that he would be asserting himself.

I agree with lotsocats. I have read that cats will mount another cat in an attempt to show dominance. That's why you will see females doing this to other females, females doing this to males, and males doing it to males - poor Blackie . Whether a cat is spayed or neutered doesn't seem to make any difference at all in this, uhm, display.

The cat that I am cat-sitting sometimes tries to sort of mount my cat when my cat is lying down. I tell my kitty - you don't have to take that . Then they start to bite each other and a chase ensues all around the apt.