Nephthys, the second daughter of Nut and born on the fifth intercalary day, was the consort of Seth, her brother, but her loyalties were with Osiris; her name means "Lady of the House" and is thought to refer to the Palace of Osiris. As the wife of Seth, the god of aridity and storm, Nephtys conceived no children. Her greatest desire was to have a child by Osiris, so by either getting him drunk or disguising herself as Isis she deceived him. The fruit of their union was Anubis; but from fear of Seth's vengeance she exposed the infant as soon as he was born. Soon afterwards Seth murdered Osiris, which caused Nephtys to flee from him. She then joined Isis in her search for the remains of the body of Osiris and told her sister about Anubis. Isis found the baby in the delta marshes when searching for Osiris, and adopted him.
Afterwards Nephthys remained with Isis during her further trials of hiding in the marches. Isis protects her, and others who have fled the horror of Seth, by giving them magical powers that enable them to transform into various animal forms through metamorphosis. When finding the parts of the body of Osiris, which Isis puts together, the two sisters embalm it; then, as kites, they mourn over the corpse. In the same way, in funerary rites when the deceased was identified with Osiris, "Nephtys" mourned at the head of the coffin, while "Isis" stood at the foot. Like Isis she enfolded and protected the deceased with her long feathery wings and was represented as such on coffins. She was said to be a friend of the dead in the judgment hall of Osiris.
In another legend after Seth succeeds in capturing Osiris body the second time and cutting it up into pieces, Isis does not stop searching until she finds the pieces. She locates all the pieces except the phallus. She enlisted the aid of Anubs, Nephthys, and other deities to create the first mummy. A.G.H.
Ions, Veronuca, Egyptian Mythology, Feltham, Middlesex, Hamlyn Publishing Group, Ltd., 1968. p. 67
Grimal, Pierre, Larousse World Mythology, Secaucus, New Jersey, Chartwell Books, 1965, p. 36