A great deal of business, in every sense of the word, was conducted between the free through slave intermediaries, constantly available as buffers, proxies, substitutes, fall-guys, and messengers. Slaves provided the free with leeway in their relations with each other, and they also enabled a set of relations shadowing those with their peers, both a convenience and a source of friction. The present chapter concerns these triangular relations between slaves and free.

Nowhere did slavery affect relations between the free more acutely than in the Roman family. The very words domus and familia had a capacious semantic range, including (sometimes, but not always) both slaves and family in a single unit. Seneca, for instance, (De Ira 3.35.1) lists slaves, freedmen and clients, together with wife, as part of the domus. It is not until modern times that such usages fade to isolate starkly the nuclear family as an affective and domestic unit. Within the Roman house, slave nurses and paedagogi would stand in for parents in some areas of the care and education of the children and, conversely, one or more of the slave familia might actually be children of the paterfamilias, and a slave or freedwoman his concubina. The legalities of the situation could get complicated, and they offered rich opportunities for the exercise of legal and rhetorical ingenuity. Martial (6.39) displays his literary wit on a wildly paradoxical menage in which it is the matrona, not the paterfamilias, who is confusing the situation: Cinna has been made a father seven times by his wife Marulla, but not a father of children/freeborn (non liberorum), for his wife has been doing the rounds of the slaves.