Outline the role of key characters:

Sigmund (vs. Lyngi, son of Hunding)

Hjordis

Alf, son of Hjalprek

Sigurd

Regin, son of Hreidmar

...tells of 'Andvari's loom'=Otter's ransom

...Fafnir and his hoard

...reforges Gram

Sigurd avenges his father

...warned by Fafnir at his slaying