blood feud

And what might not that fate be, betrayed into the hands of one who had so deadly a blood-feud with their parents!

The little semblance of law that was in the valleys below regarded it as a blood-feud, and didn't bother itself about it.

In the original story, Helgi's blood-feud was probably with the kindred of Sigrun or Svava.

That was how I talked once, before I knew what a blood-feud was.