Sick week; Prick Duke

I've been sick since Sunday, although with hindsight, Sunday was a walk in the park.  Fortunately, Duke was spending half of the week with John, and he gave me a quick lesson Wednesday, rode him Thursday, and then hacked him Friday when I was too sick to make it out.  Riding today was unpleasant; I was weak, and couldn't get enough air in my damn lungs, so gasped around like a fish out of water.
On top of that, Duke was just in a mood.  He was stubborn, leaned on me, resistant, and basically acted like John has never ridden him before, and he wasn't going to respect John in the arena either.  Eventually, John went and got his draw reins, and then Duke was miraculously an entirely different horse.  He remembered how to go round and quit and soft and bent and pliable.  Until we tried to halt, then he danced all around, unable to stand still (also when John put them on and off).  So needless to say, we didn't get to jump.
However, I did get a little more insight into the aids.  If we're going right, and I want him bent right, I am half halting with my left hand (inside leg on when I squeeze with outside hand), but I am using my right hand differently, to squeeze in release.
Then John had me halt by using my outside leg, and Duke stopped in a gorgeous, still, square halt.
So I think there's a secret to independent hands and legs that I'm on the cusp of getting that will make things better.
John also wanted heels down, BUTT IN THE SADDLE, sitting up tall, and carrying my hands.  He said I was bending my wrist too much at one point, and had me collect the reins up way more than I thought I would.
He had us work on a 20 meter circle (with Tanya), then he'd say "10 meter circle!" and we'd shoot off into the 10 meter circle, where usually Duke wouldn't be bent enough.  We'd leg yield back out to the 20 meter circle for a while and then he'd have us come back in.
Duke was just chewing chewing chewing chewing on the bit and thrashing his tail and just generally letting anyone know who looked at him that he wasn't enjoying himself.  It's weird, 99.99% of the time after John rides him, he's a delight to be on, like a purring Cadillac.