Gunpowder, Gelatin, Dynamite with a Lazer Beam

Only one things changes. It shouldn't mean much, in the grand scale of things. One chromosome shifted. The story remains the same, the players unchanging in their roles. In every incarnation, Killer is Kidd's partner, and nothing will change that.
  The story was already written. Their plight always set to follow this path. Nothing changes. Except...