In the nuclear wasteland, there are no morals, only suriviors.

[SataiRolePlayingGuy]

This is an idea in a setting very very loosely based on the world of Fallout.  A world where civilization collapsed and has only very recently begun to be reestablished in some places.  The story will explore most of the darker aspects of such a world, the story is focused on a brother and sister, with no surviving family.  Their parents were recently killed and now they are on their own and need to do whatever they can to survive.  Both are reasonably well armed at the moment, knives, several guns with ammo.  Eventually they need to replace/resupply them though.

Both will quickly learn they can only trust each other, and they have to do anything they can to survive.  Within the first few nights, the brother will cross the incest line, whether she wants to or not.  Once crossed, it will continue.  They will need to kill, both humans and non-humans.  Both will likely have varying amounts of sex with the creatures of the wilds, sometimes more willingly than others.  The brother will sometimes sell his sister for the night for money, or temporarily give her to others to avoid trouble (but will kill anyone who tries to keep her).  Sooner or later, she is likely to have one or more of his children.  Desperation for food may even lead them to cross the cannibalism line.  Just about any line might be crossed in one way or another, in a story of love and survival for a desperate brother and sister.