Most passive verbs in Greek express their agent by means of the preposition ὑπό with the genitive. The most common exception to this rule is that passive verbs in the perfect generally construe with an agent in the dative case:

Because of this anomaly, many scholars have denied that the dative found with perfect passives is an agent at all. Instead, they would describe this usage as a dative of interest. What is less clear, however, is the reason why the perfect is distinguished from the other aspects of the Greek verb in this way. The answer seems to lie in the stative nature of the perfect: if no dynamic action is being described, what place is there for an agent? Furthermore, while it is quite plain that the usage of the Greek perfect changed significantly over the period from Homer to Koine, the effects that this change had on the expression of the agent with the perfect passive have not been fully examined. As early as Herodotus, some perfect verbs have ὑπό+G rather than the dative marking the agent, notably when the subject (that is, patient) of the verb was animate. This use of the perfect passive with an animate patient becomes more frequent by the time of Polybius.