This chapter discusses the prepositional marking of the second argument in Bohairic Coptic complex verbs with the light verbs er- ‘do, make’ and ti- ‘give’. As such verbs were typically used to integrate verbal borrowings from Greek into Coptic, the question is examined if argument marking patterns in these verbs can be considered a replica of Greek valency patterns. Enhancement of already existing marking strategies is a more plausible scenario, however. As a result, the rise of complex verbs has contributed to a radical restructuring of the transitivity system in Coptic. Two competing subsystems of transitivity can be distinguished: a recessive one characterized by head marking of the second argument and emphasis on the discriminating function of case and a productive one, additionally boosted by the rise of complex verbs, in which the characterizing function of case becomes prominent thanks to dependent marking by means of a preposition.