In Old Norse society, family affiliation was nominally declared by a patronymic naming system, in which sons and daughters were customarily (though not inevitably) identified by their filial relationship to their father. Systems of kinship were thereby embedded in forms of address and reference and continually reinforced by social usage. Moreover, the patronymic system specified a certain type of relation, namely the relation of descent between a father and their son or daughter, rather than just common membership of a family group. Nominal identity thus had a dual foundation, comprised of both the bearer's distinctive singular identity as well as the identities of those to whom they were related. The use of patronymics, which embed the name bearer in a larger lineage, openly declares, even performs, the relationship between father and son or father and daughter. Conversely, such a relationship could also be denied by the rejection of such a name and the assumption of a matronymic in its stead, as when Loki is called Laufeyjarson to reinforce his kinship with his mother's family, the Æsir, rather than his kinship with the giants from whom his father, Fárbauti, is descended. The preference for a patronymic rather than a matronymic indicates the higher value placed on the patriline as compared to the matriline. Any preference for a matronymic tended to indicate something undesirable about the father, such as Fárbauti's giantish blood.

Because patronymics depended on filiation, not marriage, they were constant from birth. Even after a woman married, she would still be known as the daughter of her father. Similarly, even after a man became a father to his own sons, he would still be known as the son of his own father, his paternity reflected in his son's names rather than his own. Other names might change, as when Áslaug becomes Randalín in Ragnars saga loðbrókar or Höttr becomes Hjalti in Hrólfs saga kraka, but while a patronymic might be displaced by a character's more common nickname, once bestowed, it could not be altered.

In addition to the patronymic, of course, people also bore personal names and just as the patronymic indicated a person's descent, personal names in Old Norse could likewise be descriptive. Björn (Bear), who is turned into a bear in Hrólfs saga kraka, is so-named long before his transformation but the narrative logic behind his name is clear.