How the Vikings named their children is interesting. Every boy was named for his father and every girl was named for her mother. Thus, Leif Ericsson was the son of Eric, and Sigrid Johnirsdaughter was the daughter of Johnir. Of course, names were in the old Norse language, not English translations. For example, daughter in old Norse is dottir. There are several names for son, but one is sonr. They might also have an additional part of their name, named after an animal or an ancestor.
As adults or older children, the Vikings might gain another name that told what they did, such as Eric the Red (because of his fierceness in battle) or Lief the Lucky.
Viking names were very different and sometimes very long. It's no wonder they often addressed each other by nicknames.