We've got a 3 year old neutered male dwarf rabbit and a male kitten who is almost four months old. The kitten isn't neutered yet, but will be before he turns five months old.
The cat and the rabbit are friendly. They don't groom each other (yet - I have hope!) but they run and play together, and boop noses together sometimes. But earlier today I caught the kitten mounting the rabbit, including biting him on the scruff of his neck. The rabbit did not seem panicked; he just held still, even after I separated them. He seemed relaxed, but didn't move for several minutes.
How did the rabbit interpret this behavior? He didn't seem to mind it, so I wonder if he felt he was being groomed, as is his due as king of the house.
Was this aggressive behavior on the part of the kitty? Should we be preventing it? Should we keep them separated until the cat is neutered?