This article investigates two well-known and highly debated issues of Romance morpho-syntax, existential constructions with HAVE and pleonastic uses of reflexives (i.e., pleonastic SE) with one-argument verbs, as instantiated in some southern Italo-Romance varieties, in relation to their Latin antecedents. It is demonstrated (i) that existential HAVE in Romance continues and further develops patterns which became available in Late Latin to ‘introduce a new entity or situation into the world of discourse’ within a spatio-temporal frame and results from paths of change reflecting the existential uses of the Latin verb habere ‘have, hold’, rather than being related to an original possession scheme, i.e., to the transitive verb of possession habere, as usually assumed in the literature, and (ii) that pleonastic SE with one-argument verbs in some southern Italo-Romance varieties functions as a split intransitivity marker, continuing a Late Latin usage surfacing also in other Romance languages (e.g., French, Spanish and Romanian), albeit to a different extent.