What if they are irrational?

Does the idea of fixing the relationship before negotiating apply when the other person has severe emotional or rational issues?  I have one such relationship at the moment.  I can't easily walk away from this relationship.  I have some important things that I want, and--like it or not--I need cooperation from someone who has unhealthy emotions, impure motives, and delusional thoughts.

I think the concept still applies.  If I want the other person to cooperate with me to meet some goal, then I have to work on the relationship.  Otherwise, I have to give up on the goal.  If you want peace in the Mid-East, you either nurture your relationship with some unsavory characters or give up on peace.

So I'm going to try to work on this relationship.  Based on the book, Getting to Yes: Negotiating Agreement Without Giving In, I will need to listen to this person's perceptions, even if I'm likely to hear many things that are paranoid and unflattering.  I'll need to let this person vent his emotions and not react, even if it gets ugly.   And I'll have to listen to their point of view, even if I don't agree.  I'll try to find some truth in his perceptions, some validity to his demands, some value to his goals.  And I'll have to calmly tell him my honest perceptions of him, tell him my emotions towards him, and express my point of view, even if he doesn't like it.

Only then will we be ready to talk about how to reach any goals together.