Chepang has one of the most elaborate agreement systems in the Tibeto-Burman family. It is characterised by argument co-sensitivity, where person agreement is always with a first or second person argument in preference to a third person argument. It also has an inverse system (marked by an inverse suffix) which distinguishes the directionality of the transitive relationship. When the arguments of a transitive clause are both third person, the inverse marker may be used to indicate the topicality of a direct object argument. Caughley (1982: 56-57) notes that possessors within a possessive noun phrase can control agreement on verbs that are marked with the suffix -bət and that the distribution of possessor agreement is determined (at least in part) by information structure. He proposes (Caughley 1982: 162-3) that the original function of –bat is to indicate that ‘the Topic stands in a possessive relationship with some entity’, while the combination of –bat and the inverse –ta indicates that the topic is the possessor. When a possessed noun is ‘the given participant’ in discourse, the verb does not agree with the possessor.
Caughley, Ross Charles. 1982. The syntax and morphology of the verb in Chepang (Pacific Linguistics Series B 84). Canberra: Pacific Linguistics.