- So its a teenage thing. Pimples, rebellion, life sucking.— Sheppard grasps the Wraith life cycle.
The team arrives on a world being terrorized by an entity known as the Daimos. They infer that the Daimos is a lone Wraith hiding out in the forest, the last survivor of a crash ten years ago. They promise to kill it, and Ronon breaks out his tracking skills.
What they find is a young female Wraith and her "father" Zaddik. Zaddik explains that he found the girl, Ellia, as a child and has raised her as his own. Moreover, she no longer needs to feed on humans because of a serum he has developed, and could not possibly have been behind the attacks. Ronon, Sheppard, and Teyla go looking for the presumed second Wraith (an adult male) while Dr. Beckett is called in to examine Zaddik's serum.
Beckett in the meantime has been working on developing a retrovirus that will erase a Wraith's Iratus bug DNA, effectively turning them human. He hopes that Ellia's cooperation will help him improve the retrovirus to the point of practicability (since right now it is incomplete). It turns out, though, that Zaddik's serum never actually worked on Ellia, and she's been masking her own feeding by going out at the same time as the other Wraith. When they kill the other, she won't be able to hide anymore. So, when Zaddik and Beckett leave the room briefly, she injects herself with the retrovirus.
The others manage to kill the adult Wraith without too much effort, but not before it has fed again, bringing the villagers out in force. Unfortunately, the retrovirus has had exactly the opposite effect on Ellia of the one intendedit starts overwriting her human DNA and turning her into something more like the Iratus bug, with vastly increased strength and scary claw-like hands. Zaddik tries to reason with her, but in her animalistic state she throws him off, wounding him fatally. Sheppard and Ronon pursue her into the woods, but she manages to grab hold of Sheppard's arm, (presumably) feeding off of him, Iratus bug-style. Ronon arrives and shoots her off of him, and the two are forced to kill her.
- Bizarre Alien Biology: Zaddik's experience with Ellia allows Beckett to determine that the Wraith possess a human digestive system because they consume food in a more conventional manner as children, only developing the need to feed in their teens.
- Call-Back: To the episode "Thirty-Eight Minutes", with the reference to the Iratus bug that nearly killed Sheppard.
- Fantastic Racism: Demonstrated by Ronon, who immediately hates Ellia just because she's a Wraith even though she actively tries to be something more.
- Good Parent: Zaddik provided shelter for his adoptive Wraith daughter, taught her right from wrong, and even offered himself as nourishmentagainst her objectionswhen food no longer sustained her.Zaddik: Then the hunger came. She took what she needed from me to survive.
- "I Know You Are in There Somewhere" Fight: Zaddik tries this with Ellia
- Luke, You Are My Father: Zaddik reveals himself to be the presumed-dead son of the village leader. The reason they look the same age? Zaddik let Ellia feed off of him until he could develop his serum.
- Sacred Hospitality: The tavern keeper believes he has a responsibility to provide food and shelter to unwary travelers.
- The Virus: Beckett's retrovirus, one way or the other.
- Torches and Pitchforks
- What Measure Is a Non-Human?: Ronon dismisses Ellia as 'just' another Wraith, but Teyla recognises that Zaddik has managed to instill human values in her, even if she is ultimately overwhelmed by her mutated nature.
- Younger Than He Looks: Zaddik is maybe thirty, but he looks around sixty because he allowed Ellia to feed off of him.