I would say move him. He seems like the "bottom" guy, and intertwined is one that has taken over that doesn't know how to quit. My friend was (old neighbor) was training a horse that was very dominate/aggressive toward other horses (leaving marks like this). With my permission, she pastured him in with my mare and a large, older gelding (he was a stud for awhile). The two of mine were very dominate, but not aggressive (they would only go so far as to make their point, then quit).
First thing, the big 16+ h gelding I had put 2 back hooves straight to the head when the trainee charged/challenged him and wouldn't let up. After a month, she put him back in with the other horses she had, and didn't have near as many problems. (It was actually very fascinating to watch the difference it made in his total attitude)
Sounds like yours is unfortunately paired with one of those. If that horse doesn't "know when to quit" and the owner/BO is not willing to do anything about it, you need to get yours gone. Those bites are beyond what's really normal. My horses get bites on them every so often, but nothing near that bad. I would be EXTREMELY concerned if that were to happen, let alone on a regular basis.
My horses all share the same hay ring and pasture (Course there are only 3, I plan on boarding up to 2 additional for extra money, but in that case I would get an additional hay ring, and I have to get things set up here). Only 1 is technically mine, actually. They pick on each other, kick, bite, run, play, etc. I fine the stray hoof or teeth marks that break skin but not regularly and not bad.
I'd move him out, take the hit, and then see if there's anywhere closer in the long term. I'd move him sooner than later, tho.