> "Þeir einir munu vera," segir hann, "að eg hirði aldrei þó að drepist."
> 'They will be alone (on their own?),' he says, `(such) that I never

cared even though (they) kill-each-other.'

'einir' = "only" here: "It will only be such people that I don't care
even if they kill each other."