That is, I trust you because your interest encapsulates mine, which is to say that you have an interest in fulfilling my trust. It is this fact that makes my trust more than merely expectations about your behavior. Any expectations I have are grounded in an understanding (perhaps mistaken) of your interests specifically with respect to me. … More generally, it is principally those with whom we have ongoing relationships that we trust. In addition, the richer an ongoing relationship and the more valuable it is to us, the more trusting and trustworthy we are likely to be in that relationship.

Russell Hardin, Trust and Trustworthiness, loc. 66