I honestly do think it stems from not being spayed. Seriously, the tension between Pouncer and Abby started long before she actually started a heat cycle. She was spayed before her first heat (but I swear given a few more days and she would have gone into heat! ) She was giving off hormone that he was reacting to and even after she was spayed, the behavior stuck as a "game" for him.

What I did was just keep them apart as best as possible. If I saw him starting a sneak attack on her, I yelled out "Don't even THINK about it!" and he would either stop dead in his tracks or continue on his attack and I'd have to rescue a screaming Abby.

Then, after a year of this behavior, I noticed SHE would BAIT Pouncer. When he'd take the bait, she'd start screaming, I'd rescue her, and all was good again. You know what? Ever since I noticed that, I began to ignore her reactions to him. I didn't rescue her. I didn't tell him to leave her alone. And guess what? The behavior has dramatically decreased! She realized she wasn't going to get my sympathy any longer and she stopped baiting him.