house sitter: a custodian who lives in and cares for a house while the regular occupant is away (usually without an exchange of money)
custodian: one having charge of buildings or grounds or animals
hippocampus: a complex neural structure (shaped like a sea horse) consisting of grey matter and located on the floor of each lateral ventricle; intimately involved in motivation and emotion as part of the limbic system; has a central role in the formation of memories