"All humans desire power. It's just that most of them are never in a position to attain it."
— Replicarter
Carter's replicator double contacts the SGC with a surprising request: she wants them to kill her. Carter suggests that they hold off on destroying her to get more information when she reveals that Fifth plans to take over the Milky Way, but O'Neill and Teal'c are concerned that her empathy for the clone could prove dangerous.
"Gemini" provides examples of the following tropes:
- An Arm and a Leg: Replicarter deliberately separates her own arm in order to escape when Teal'c grabs her as she's going through the stargate.
- Batman Gambit: Replicarter's plan relies on Carter empathizing with her and on the humans as a whole being curious enough about what she knows that they don't kill her the second she steps through the gate. Justified, since her brain is modeled after Carter's so she can accurately predict her behavior.
- Bottle Episode: Uses a small cast and takes place entirely indoors, either at the alpha site or the SGC.
- Breaking Speech: Replicarter to Carter, once her true agenda has been revealed:Replicarter: You have untapped greatness inside you, Sam, but you're limited by your own fears. You play by the rules, you do as you're told and you deny yourself your own desires.
- Chronic Backstabbing Disorder: Replicarter betrays both Fifth and her human counterpart in short order.
- Continuity Nod:
- Carter points out that none of this would have happened if they hadn't betrayed Fifth in the first place.
- The Replicator disruptor reappears.
- Create Your Own Villain: Carter lampshades this at the end of the episode:Carter: The fact is, she learned betrayal from Fifth, and he learned it from me.
- Evil Twin: Replicarter is one for Carter. She specifically points out that they don't just look the same, they have the same memories and their brains are wired to think in the same way.
- Finish Him!: Said by Fifth when Replicarter hesitates to kill a virtual O'Neill in the vision she shows to Carter to gain her trust.
- Foreshadowing: Daniel talking about wanting to go to Atlantis in the opening scene sets up the events of the next episode.
- Hive Mind: Replicarter makes use of the replicator hive mind to communicate with Fifth without alerting Carter and Teal'c.
- Hoist by His Own Petard: Fifth is betrayed and killed by his own creation.
- I Cannot Self-Terminate: Replicarter originally makes contact with the SGC asking them to kill her with the disruptor since her identity as Samantha Carter is at total odds with the fact that she's a replicator. Turns out to be a subversion, however, as she has no intention of letting herself be killed and this is all part of her ploy to make Carter trust her.
- Kill the Ones You Love: In the vision that Replicarter shows Carter, Fifth has her kill simulations of O'Neill and Daniel (and Siler) to break her emotional ties to her human life. Again, however, it seems likely that this was a fabrication on the part of Replicarter to gain Carter's trust.
- Killed Off for Real: Fifth.
- My God, What Have I Done?: Said almost verbatim by Carter when she realizes she's been played.
- Nice Job Breaking It, Hero: Carter inadvertently gives her double everything she needs to make herself — and eventually, all the Replicators — immune to the disruptor.
- No-Sell: Teal'c finally uses the disruptor on Replicarter and by then it has no effect whatsoever.
- "Not So Different" Remark: Replicarter tries to invoke this by claiming that Carter has the exact same potential for ambition, she just lacks the initiative to take what she wants.
- Out of Focus: Daniel is absent for most of the episode.
- Playing Both Sides: Replicarter effortlessly plays both Carter and Fifth, with neither of them being aware that she has her own, separate agenda until she's betrayed them both.
- Properly Paranoid: Early on, O'Neill suggests that RepliCarter might be lying about the Replicators' immunity to the disruptor, but relents to Carter's opinion that she's being honest. He's proven right, as it's revealed that there was no immunity - until the SGC let RepliCarter study the weapon, thus giving her a chance to create one.
- Psychopathic Manchild: Carter describes Fifth as such, claiming that for as powerful as he, mentally and emotionally he's an unstable teenage boy.
- Simultaneous Arcs: This episode and "Prometheus Unbound" are both taking place at about the same time.
- Stalker with a Crush: Carter correctly deduces that Fifth created a replicator in her likeness because of his "feelings" for her.
- The Starscream: Replicarter kills Fifth in order to take over the galaxy herself, as she deems him weak and unworthy to rule.
- Technopath: Replicarter can interface directly with the computer by sticking her hand into it, the same as she can do with the human brain.
- That's What I Would Do: Replicarter uses this to taunt Carter at the end of the episode, pointing out that no matter what the latter does to try and stop her, they think the same and she will always be one step ahead. Of course, it goes both ways.
- Trust Password: Replicarter talks about several of Carter's childhood memories as another way of gaining her trust when they first meet.
- Twin Threesome Fantasy: When Replicarter states that there are two Samantha Carters in her introduction, O'Neill says, "If only."
- The Worf Effect: Replicarter pretty much wipes the floor with Teal'c.
