Genius; In Roman mythology, the genius was originally the family ancestor who lived in the underworld. Through the male members he secured the existence of the family. Later, the genius became more a protecting or guardian spirit for persons. These spirits guided and protected that person throughout his life. Every man had a genius, to whom he sacrificed on birthdays. It was believed that the genius would bestow success and intellectual powers on its devotees. Women had their own genius, which was called a juno. Juno was also the name for the queen of the gods. However, not only individuals had guardian spirits: families, households, and cities had their own. Even the Roman people as a whole had a genius. The genius was usually depicted as a winged, naked youth, while the genius of a place was depicted as a serpent.
The Larvae also are Roman spirits of deceased family members. These malignant spirits dwell throughout the house and frighten the inhabitants. People tried to reconcile or avert the Larvae with strange ceremonies which took place on May 9, 11, and 13; this was called the "Feast of the Lemures". The master of the house usually performed these ceremonies, either by offering black beans to the spirits or chasing them away by making a lot of noise. (Like we do at Newyear.) Their counterparts are the Lares, friendly and beneficent house spirits.
Lares; Roman guardian spirits of house and fields. The cult of the Lares is probably derived from the worshipping of the deceased master of the family. It was believed that he blessed the house and, by his presence, brought fertility to the fields. Just like the Penates, the Lares were worshipped in small sanctuaries or shrines, called Lararium, which could be found in every Roman house. They were placed in the atrium (the main room) or in the peristylium (a small open court) of the house. Here people sacrificed food to the Lares on holidays. In contrast to their malignant counterparts the Larvae (Lemures), the Lares are beneficent and friendly spirits. There were many different types of guardians. The most important are the Lares Familiares (guardians of the family; Familiar spirits), Lares Domestici (guardians of the house), Lares Patrii and Lares Privati. Other guardians were the Lares Permarini (guardians of the sea), Lares Rurales (guardians of the land), Lares Compitales (guardians of crossroads), Lares Viales (guardians of travelers) and Lares Praestitis (guardians of the state). The Lares are usually depicted as dancing youths, with a horn cup in one hand and a bowl in the other. They usually were accompanied by symbolic serpents.
The Arabic counterpart of a Genius is the Jinn, known to the Greek as a Daemon.