What inhibits two people from making an agreement? There has been extensive academic work on psychological factors playing into mediation and bargaining, but not as much on how mediator bias might trigger psychological reactions that hinder (or facilitate) agreement. This paper seeks try to figure out what both rationalist and psychological arguments are missing in order to expand on them and reconcile these two different, yet not incompatible, views on bargaining. My argument is that the outcome of mediation depends on the presence of two variables: mediator bias and empathy and fairness. In particular, I argue that successful mediation requires both mediator bias and mediator’s ability to display empathy and fairness. This is because mediator bias is necessary for convincing the side one is biased towards to get along with the proposed agreement, while at the same time empathy and fairness are required for convincing the side one is biased against (or simply the opposing side) to get on board with the negotiation in the first place. Three further arguments stem from this point: that mediation will fail when mediator bias is present but the mediator fails to display empathy and fairness; that regardless of display of empathy and fairness, mediation will lead to unsatisfactory results in the absence of mediator bias; and lastly, that mediation will succeed when both mediator bias and mediator’s ability to display empathy and fairness are present.