I wouldn't profess to be an expert, but my male PD developed a bit of an agressive streak during his first year's rut, and it was still present a little towards the end.
The way I got around it was by dominating the little bugger. Disciplining him by placing him by himself in a tall bin with a lid IMMEDIATELY after anything as agressive as a bite will soon teach him not to do that. It may take a few tries, but it does work.
As for the general agression, simply not spending time with them does seem to make them less likely to be excited by your prescence.
I've found the great thing with PDs is because they're smart, they can pick up on attitude changes quickly. I wouldn't be surprised if you spent more time with them, let them out the cage, fed them etc. that within a few days you'd have your pal back.