Aggression? Dominance? Or Something Else?

[EmersonandEvie]

Emerson has started to grab Evie by her scruff and pin her down while trying to get into a mounting position. Evie hollers, but lets him do it. He only stops when we yell at him, then he walks away like nothing happened.

All my cats are fixed. Evie and Emerson are 5-year-old littermates and have never been separated. Dexter is 3. I have never noticed this behavior until a few months ago.

Any insight would be appreciated!

 

[vince]

This definitely happens; I've read about it several times here at TheCatSite. I have one now that tries to mount his "sister." Both are fixed and he really acts like he doesn't know how to do it. In my case, the female eventually gets tired of this, gives him a nip and some swats and runs off. Gradually, the behavior has been dying out with time. Mine are about five and three years old now, and it's been going on for a couple of years.

Otherwise, they're quite closely bonded. I can only attribute this behavior to be sexual in nature.