
In ancient Rome there were many slaves. It was theoretically possible for slaves to eventually buy their freedom. This was different than what we currently think of as slavery. Obviously there would have been abuses of this Roman system but it was wide spread, culturally accepted, and in some cases desirable to the alternative. The NTC on First Peter quotes Arthur A. Rupprecht on Roman slavery:
The living conditions of many slaves were better than those of free men who often slept in the streets of the city or lived in very cheap rooms. There is considerable evidence to suggest that the slaves lived within the confine of their master's house. They usually lived on the top floor of their owner's city house or country villa. In Pliny's Laurentian villa the quarters for the slaves and freedmen were in a separate section of the house, but were considered attractive enough to be used for the entertainment of over-night guests.
The slave was not inferior to the free men of similar skills in regard to food and clothing. That most slaves in Rome were as well dressed as free men is indicated in an unusual way. Seneca stated that legislation was introduce in the Senate that slaves should be required to wear a type of clothing that would distinguish them from free men.
the slaves in 1 Peter 2:18 are oiketai which is house servant or house slave.
