What makes you think he has to offer anything for a settlement? He might have made an offer if you had indicated any intention of doing so, but your refusal to negotiate means he pretty much HAS to go to court.
The proof of debt would be some document that indicated you were obligated to the debt and the "chain of title" (not really the best term here) is that the debt was indeed transferred to them so that they have the authority to collect upon it.
Unfortunately, you've not indicated anything USEFUL here.
What sort of debt was it?
Do you dispute the validity of it?
What were the time frames involved (when did you default on the debt? when was the court case filed)?
Do you have reason to believe the current debt holder has been assigned the debt?
These are the first questions a lawyer would likely ask.
Frankly, unless you seem to have some indication that you shouldn't OWE this money, it's not clear what anybody can do for you.

