[Fritz Leiber][1]'s novella "[Night of the Long Knives][2]" features a couple (man and woman) of "deathlanders" who ambush a pilot early in the story which then goes from there.

The man is older than the woman, but they are not related.

The story opens:

> I was one hundred miles from Nowhere--and I mean that literally--when I
spotted this girl out of the corner of my eye. I'd been keeping an extra
lookout because I still expected the other undead bugger left over
from the murder party at Nowhere to be stalking me.
> 
> I'd been following a line of high-voltage towers all canted over at the
same gentlemanly tipsy angle by an old blast from the Last War. I judged
the girl was going in the same general direction and was being edged
over toward my course by a drift of dust that even at my distance showed
dangerous metallic gleams and dark humps that might be dead men or
cattle.
> 
> She looked slim, dark topped, and on guard. Small like me and like me
wearing a scarf loosely around the lower half of her face in the style
of the old buckaroos.

The story is available on [Project Gutenberg][3] and there is an audio version on [Librivox][4].


  [1]: http://www.isfdb.org/cgi-bin/ea.cgi?38
  [2]: http://www.isfdb.org/cgi-bin/title.cgi?57307
  [3]: http://www.gutenberg.org/ebooks/25024
  [4]: https://librivox.org/the-night-of-the-long-knives-by-fritz-leiber/