One of the oldest stories of the Aesir:
The Saga of the Volsungs
Sigi, the son of Odin, murdered another man's thrall (slave) so he was named an outlaw and banished from the land. His father took care of him and led him to Hunland where he became king. Eventually, he had a son named Rerir. While Rerir was away, Sigi was attacked and killed by his wife's brothers (a recurrent theme in this saga). When Rerir returned, he reclaimed the throne and married.
He and his wife could not reproduce so they prayed to Frigg for fertility. Frigg told Odin about the couple's request so Odin called one of his wish maidens (possibly a valkyrie), the giant Hrimnir's daughter, and gave her an apple. She turned into a crow (a woman turning into a bird or putting on its feathers was common in norse lays) and droped the apple onto Rerir's lap. Rerir took the apple with him on a visit to the queen, and ate some of it. The queen soon bore Volsung He married the aforementioned wish-maiden who was named Hljod.
Hljod and Volsung had ten sons, the eldest named Sigmund, and one daughter, Signy . Volsung had a palace built around the tree Branstock so that the trunk of the tree was in the palace. The King of Gautland (Sweden), Siggeir , asked for Signy's hand. At the wedding banquet, Odin arrived in his usual disguise -- elderly, one-eyed, wearing a cape and hood --, stuck a sword in Branstock and said whoever pulled the sword out could have it. All tried, but only Sigmund prevailed. Siggeir wanted the sword and plotted revenge against Sigmund. He invited the King and all of his sons to visit the newly weds in Gautland in three months.
After the Volsungs arrived, Siggeir and his army attacked them. King Volsung was killed and all of his sons taken prisoner. Signy asked her husband to put her brothers in stocks instead of killing them quickly. Siggeir agreed since he thought they deserved to be tortured. For nine nights a she-wolf, Siggeir's shapeshifted mother, ate one of the Volsungs, until only Sigmund remained. Signy had her trusted man-servant smear honey on Sigmund's face and in his mouth. That night the wolf licked the honey and when it stuck its tongue into Sigmund's mouth, he bit it off, killing the wolf.
Siggeir thought all the Volsungs were dead, but Sigmund lived in the forest underground. Signy brought him everything he needed. She had two sons with Siggeir and sent the eldest when he was ten to Sigmund to aid in the revenge of Volsung. Sigmund tested the boy's courage by asking him to knead flour which had something alive in it. The boy would not touch the flour so Sigmund didn't want him as a helper. Signy told Sigmund to kill the boy, since he was worthless. Sigmund did so. The same happened with Signy's other son.
Signy exchanged shapes with a beautiful sorceress and went to Sigmund. The two slept together and Signy later had Sigmund's son, Sinfjotli.
© 1996, Nicole Cherry
(Editors Note: The Aes were/are an odd bunch, from the Vanir perspective anyway)