The person-case constraint (PCC) is a family of restrictions on the relative person of the two objects of a ditransitive. PCC effects offer a testing ground for theories of the Agree operation and of syntactic features, both those on nominals and (of special interest here) those found on agreement probes. In this paper, I offer a new theory of PCC effects in an interaction/satisfaction theory of Agree (Deal 2015a) and show the advantages of this framework in capturing PCC typology. On this model, probes are specified for interaction features, determining which features will be copied to them, and satisfaction features, determining which features will cause probing to stop. Applied to PCC, this theory (i) captures all four types of PCC effect recognized by Nevins (2007) under a unified notion of Agree; (ii) captures the restriction of PCC effects to contexts of “Double Weakness” in many prominent examples, e.g. in Italian, Greek, and Basque, where PCC effects hold only in cases where both the direct and indirect object are expressed with clitics; (iii) naturally extends to PCC effects in syntactic environments without visible clitics or agreement for one or both objects, as well as the absence of PCC effects in some languages with clitics or agreement for both the direct and indirect object. Two refinements of the interaction/satisfaction theory are offered. The first is a new notation for probes’ interaction and satisfaction specifications, clarifying the absence from this theory of uninterpretable/unvalued features as drivers of Agree. The second is a proposal for the way that probes’ behavior may change over the course of a derivation, dubbed dynamic interaction.