In some of the Icelandic sagas in which he appears, Bjarni Brodd-Helgason is a generally peaceful man, even though he got the nickname Víga-Bjarni (Killer-Barney) when he had to kill some of his relatives at Bodvarsdalr. In Vápnfirðinga Saga he is reluctant to take revenge; he is eager to reconcile in Voðu-Brands þáttr; and he’s clever and honorable in Þorsteins þattr stangarhoggs. So the nickname is somewhat at odds with the character, especially in these sagas that come from the East, where Bjarni was from. The disjunction between name and personality seems to be the point, especially in Thorstein the Staff-struck.
Víga-Bjarni’s name, however, appears to have overpowered his character in later sagas from the West, where people either had not known Bjarni Brodd-Helgason, or the transmitted knowledge of his personality was forgotten. In this material, Killer-Barney is now a blood-loving, death-dealing maniac.
I hate you,
you hate me,
I had to slaughter members of my family....
We can call this phenomenon, in which a traditional referent, like Víga-Bjarni's name, loses the link with its original extra-textual and contextual meaning and instead develops as part of a new, intra-textual tradition, The Killer-Barney Effect.