It is argued by Hettrich (1990) that the "dative of agent" construction in the IndoEuropean languages most likely continues a construction inherited from ProtoIndo-European. In two recent proposals (Danesi 2013, Luraghi 2016, it is argued that the "dative of agent" contains no agent at all, although the two proposals differ with regard to the reconstructability of the "dative of agent" construction. Luraghi argues that it is an independent secondary development from an original beneficiary function (cf. Hettrich 1990), while Danesi maintains that the construction is reconstructable for an earlier proto-stage. Elaborating on Danesi's approach, we analyze gerundives with the "dative of agent" in six different IndoEuropean languages that bridge the east-west divide, namely, Sanskrit, Avestan, Ancient Greek, Latin, Tocharian, and Lithuanian. Scrutiny of the data reveals similarities at a morphosyntactic level, a semantic level (i.e. modal meaning and low degree of transitivity), and also, to some extent, at an etymological level. An analysis involving a modal reading of the predicate, with a dative subject and a nominative object, is better equipped to account for the particulars of the "gerundive + nominative + dative" construction than the traditional agentive/passive analysis. The proposal is couched within the theoretical framework of Construction Grammar, in which the basic unit of language is the Construction, i.e. a form-function correspondence, and no principled distinction between lexical items and complex syntactic structures is assumed. As these structures are by definition units of comparanda, required by the Comparative Method, they can be successfully utilized in the reconstruction of a protoconstruction for Proto-Indo-European.