Person based restrictions on combination of two internal argument clitics known as the Person Case Constraint (PCC) show two types of variation: (i) Different languages and different groups of speakers within one language allow differ combinations of person on the two internal argument clitics, and (ii) languages differ on which of the two arguments is realized differently when cliticization of both is blocked by the PCC. Two types of proposals exist within the larger literature on person based restrictions for how the first type of variation arises. Multiple Agree analyses locate the variation in the parametrization of the operation Agree. Cyclic Agree analyses on the other hand locate the variation in the properties of the functional lexicon, specifically the feature content of the probe and its syntactic position. Case studies of Central Catalan and Classical Arabic demonstrate here that a Cyclic Agree analysis using different feature specifications on the probe can account for variation of the first type between the Strong PCC and the Ultrastrong PCC within each of the the two languages. Cyclic Agree thus offers a unified analysis of such variation in the PCC and in person restrictions between subjects and objects where it was originally proposed (Bejar & Rezac 2009). The second type of variation is shown to arise from the different underlying structures that cause PCC in Central Catalan and Classical Arabic. A Cyclic Agree analysis offers a way of understanding this variation in terms of the different positions of the probes, different locality patterns of Agree as a function thereof and the presence of other processes of movement and Agree. The alternative strategies used when the PCC blocks cliticization are argued to follow from independent derivational processes, rather than a Last Resort mechanism. The analysis of the PCC is also shown to extend to restrictions on combinations of third person pronouns that are not typically analyzed in the PCC literature. Cyclic Agree thus accounts for some of the variation of the first type, plus the second type and restrictions on combinations of third person pronouns.