Slash or Gen. John/Rodney or John&Rodney friendship.
Prompt: After an accident, John (or Rodney) was turn into some kind of creature that only feed on Wraiths. (Not like how the Wraith feed on human, no.) Moreover, every time a Wraith comes within 10 feet of John (or Rodney), it either wants to fight/flight or, in most case, paralyzed with terror. Everyone should be pleased with this change, but Rodney (or John) doesn't.