The Son of Chaos.

EDIT: Removing post since circumstances cleared up, so ill save the pointless read.

yeah you can always do that. You can do it while he;s on full hp. Thats how a lot of people kill him.

Oh wasnt aware of that, since i did this fight 7 times now and it never happened before lol.

Well might as well disregard the post then, though makes me wonder whether the other method is actually a glitch, and if it is not, whether this method is a glitch, i mean miyazaki did say that the boss fight is optional, so retreating to stop the fight in the first place and never starting it, leads to the same end result.

skarekrow13 wrote:I was really hoping I would be able to resume in the arena by using homeward bone and stepping inside and doing the quit/reload trick. Sadly I had done just about everything I could think of with what I had in the arena. Was hoping undead rapport when he's asking you to kill him would do something or that Oscar had left me a message there. Might have to do another playthrough eventually :x

You can resume (after picking up the clothes and leaving the arena) if you already did the waiting period and reload trick:
After entering the fog, sprint into the shortcut and wait until he tries to punch you there. Run when he starts the attack and stop close by the wall where you respawn, and he will slowly make his way back towards you. Wait there for 10+ seconds before you quit/reload (quit in the middle of his attack) and you should respawn inside the arena with him docile again.

I also saw this a while back, he falls at the same time the player falls down. It could just be coincidental, but still interesting.
https://www.youtube.com/watch?v=cHWCVLwrNJI