Thanks Aluz and Jonah,
I separated them today as the commotion was just becoming unbearable and both birds were visibly exhausted from all the chasing (though Frankie STILL pursued). I was a bit surprised too; normally when I try to intervene, the birds respond to me as the common threat and will stop antagonizing each other. But this time, even when trying to grab him with a towel, Frankie was totally un-phased. Not afraid of me at all. Just kept trying to get at Beemo.
They have a pretty large cage for the two of them - about 2 feet square by 3 feet high. Plenty of perches, food dishes, toys, etc. And it never seems like Frankie is trying to chase Beemo away
. He's always just trying to get to
Beemo. No matter where he is in the cage or outside it.
Overall it seems like a very abusive little friendship. Though I haven't seen them do it recently, they did used to preen each other, and Frankie does still feed Beemo. But 80% of the time, Frankie is just chasing Beemo all over the place pretty relentlessly and does peck at his head a lot, especially in the mornings.
Anyway, I'm gonna keep them in separate cages for a while again. Might have to try for a longer period of separation this time. Thanks again for taking the time to respond.