Many races of the fey folk chose to give their services to mankind. These ranged from small, one-time tasks and gifts to daily hard work tilling fields or performing domestic chores. However, several taboos were placed upon the beneficiaries of fairy help and the etiquette should be scrupulously respected.
First, thanking or rewarding the fairy was strictly taboo. To do so almost always either offended the fairy into leaving, or (as in the case of fancy clothes) caused the fairy to realize the menial nature of his work and to leave to pursue more gentlemanly pursuits. The restriction against rewards only applied to gifts outside the original agreement between the master of the household and the fairy.
The second task that must be faithfully followed by the people whom the fairies help was leaving out a nightly bowl of cream or milk. In the North Country, brownies liked to enjoy its nightly bowl as well as a honey cake or other sweet tidbit. This was a necessity, for if one skimped on the fairy's nightly meal, the fairy would grow angry and resentful.
The third restriction that was to be followed was to respect the fairy's privacy. This was not always required for all fairies, but many preferred to work in private. Spying on them through peepholes, talking to them directly, and telling others about the family fairy were all things which could offend the fairy in question.
Living with faeries