[quote=tchtkrmkc]
I'm sorry if I should know this, but to daemon hunters have super human abilities? 
And why would daemons help hunters kill other daemons? 
Why do the hunters agree to work with daemons, the same things they hunt?
[/quote]

There are no super powers. Hunters are more talented than your average human when it comes to hunting daemons, but there are not special super powers like superspeed/levitation/etc.

Because they've signed a contract with a human in exchange for a portion of the human's lifespan. They're obligated to assist the human in the human's endeavors and at the end of the day, daemons are like humans to an extent. Humans kill one another, daemons would be no exception seeing as they are simply twisted forms of humans.

Hunting a daemon is much more dangerous without a daemon. Daemons are an integral part of the process when it comes to hunting other daemons. Without one the hunter would be at a tremendous disadvantage.

That's how I envision it, though I may be wrong.