History Recap / StargateSG1S6E12UnnaturalSelection

* TheSocialDarwinist: First has shades of this, comparing a replicator conquest of the galaxy to humanity's position as the dominant species on Earth, claiming that it only makes sense for the strong to subjugate the weak.

* PlotHole: It is stated that the other human-form Replicators have inherited the flaw in Reese's programming, but their stoic attitude is directly opposite her childlike and emotional behavior and capacity for empathy. Fifth, in whom the flaw was supposedly correct, behaves much more like Reese.

SG-1 and the ''Prometheus'' are recruited by Thor to battle replicators that have taken over a planet in the Asgard home galaxy, but are soon taken captive by a new line of sentient, human-form replicators who intend to use the team's knowledge to help them achieve their goal of conquering other worlds.

* AdmiringTheAbomination: Jonas finds the idea of replicators "fascinating" before (and to an extent, after) he actually comes face to face with them.

* BlueAndOrangeMorality: Teal'c describes the replicators as this.

** Thor mentions that the Asgard have been studying the [[Recap/StargateSG1S5E19Menace android Reese]] for a means to combat the replicators.

* FauxAffablyEvil: The human-form replicators, especially First, who remains polite and charming even while mind-raping the team.

* HiveMind: Fifth states that the human-form replicators have a shared consciousness and can mentally control the regular replicators.
* MindProbe: The human replicators do this by shoving their hands into the heads of the team (though as Fifth shows, they don't strictly have to), creating [[MentalWorld dreamlike worlds]] from which they can extract the required information.

* NiceJobBreakingItHero: The Asgard attempt to trap all of the replicators inside a time dilation field, but don't count on the replicators using the technology against them and altering the machine so that time inside the field is ''sped up'' rather than slowed down, allowing them all the time they need to create more and more of themselves.
* NoMrBondIExpectYouToDine: The replicators invite the team for a meal and insist that they eat, though they make no pretenses about the fact that they're only doing so to ensure that they have the energy to withstand repeated bouts of MindRape.
* NoSell: After First drops the bombshell that he and the others are replicators, O'Neill, Teal'c and Jonas open fire while they endure the hail of bullets without a flinch.

* RidiculouslyHumanRobot: The human-form replicators.
* ShootTheDog: O'Neill and Carter betray Fifth, promising to take him with them and then abandoning him in the time dilation field with the others after he helps them escape. O'Neill insists that [[IDidWhatIHadToDo they didn't have a choice]], however, given what the consequences could be if any of the replicators were allowed to escape.

* TokenGoodTeammate: Fifth is the only one of the human-form replicators to demonstrate empathy and compassion as a result of First attempting to correct the "design flaw" in Reese's programming during his creation. Carter even says that he seems "almost human" compared to the others.

* YearInsideHourOutside: The Asgard attempt to trap the replicators using a TimeDilation machine to invert this, but the replicators manage to hack the device so that it plays the trope straight, requiring the team to go in and fix the problem.

* ContinuityNod: Thor mentions that the Asgard have been studying the [[Recap/StargateSG1S5E19Menace android Reese]] for a means to combat the replicators.

* WhatTheHellHero: Once they're safely away, Carter and Jonas call O'Neill out on betraying Fifth. He defends the decision by arguing that they didn't have any other options, and that Fifth was ultimately as dangerous as the others.

* BigEater: O'Neill catches Teal'c and Jonas hanging out in one of the storage rooms on board the ''Prometheus'', gorging themselves on ice-cream before it can have a chance to melt. Teal'c in particular becomes very possessive after O'Neill tries to steal some, and then takes O'Neill's carton after finishing his own.

* ShootTheDog: O'Neill and Carter betray Fifth, promising to take him with them and then abandoning him in the time dilation field with the others after he helps them escape. O'Neill insists that they didn't have a choice, however, given what the consequences could be if any of the replicators were allowed to escape.

* AdmiringTheAbomination: Jonas finds the idea of replicators "fascinating" before he actually comes face to face with them.

* BluntMetaphorsTrauma:

* CallBack: O'Neill asks if Thor needs th team to come up with [[Recap/StargateSG1S4E1SmallVictories another dumb idea]].

* MindProbe: The human replicators do this by shoving their hands into the heads of the team, creating [[MentalWorld dreamlike worlds]] from which they can extract the required information.

-->'''-- Col. Jack O'Neill'''

-->'''Teal'c:''' Replicators exist merely to increase their numbers and do so without prejudice. They are no more evil than a virus.
-->'''O'Neill:''' A really ''evil'' virus.

-->'''Thor:''' If you wish to reconsider --
-->'''O'Neill:''' No, no. I full well expected the other shoe to drop eventually.
-->'''Thor:''' We can only hope that this will be the last footwear to fall.
* CallBack: O'Neill asks if Thor needs th team to come up with [[Recap/StargateSG1S4E1SmallVictoriesPart2 another dumb idea]].

-->'''O'Neill:''' You might wanna get upstairs and punch one on the old speed dial.
-->'''Hammond:''' My grandchildren?
-->'''O'Neill:''' ...''Two'', then. I think the President might wanna know what the Asgard have in mind for our new ship.

* YearInsideHourOutside: The Asgard attempt to trap the replicators using a TimeDilation machine to invert this, but the replicators manage to hack the device so that it plays the trope straight, requiring the team to go in and fix the problem.

* ContinuityNod
** Thor mentions that the Asgard have been studying the [[Recap/StargateSG1S5E19Menace android Reese]] for a means to combat the replicators.