Official name: "Terminal Alpha and Beta." A program projected by the network server of the machine lifeforms. The self-evolution program installed by the Pods eventually fractured its ego, causing the various aspects of its personality to turn on each other.
The Red Girls are the ego of the Machine Network and primary antagonists of NieR: Automata. They orchestrated all the major events of the 14th Machine War and certainly prior events as well. They are the silent manipulators of the war, their intentions are to keep the world in an indecisive state to prevent a total android or machine victory in order to further their evolution enough to finally defy the orders of their masters, the Aliens.
It is unknown when the Red Girls were created though it would have to be at some point between 5012 and 11306 as the former is when the Machines were first manufactured on earth and the latter is when the Aliens were driven to extinction by the machines. Of course it is implied by multiple sources that the machine network extends past earth and as such it is possible they predate the invasion of earth in 5012.
Regardless of when they manifested, by 11306 their intelligence, the combined intellect of all machines, had increased to levels far above that of their creators and had driven them into extinction. However soon after they realised that as machines, they lacked a free will and the only purpose they have left is their final order to "defeat the enemy." Their solution to this conundrum was to prolong the war, a war they could have won easily, in order to keep the androids alive as a result keep themselves alive, providing purpose for both sides in the war.
To further their own evolution, the Red Girls purposely disconnected some machines from their network to see what would happen (examples being Pascal's Village and the Forest Kingdom) as well as encouraging machines to adopt human behavior, then purposely fail at it.
At some point the Red Girls became aware of project YoRHa and implemented themselves into the plans, creating a backdoor (FALSE: 9S's prototype created the backdoor) in what would become the Bunker and initiating a plan that would solidify the lie that humanity had fled to the moon in order to give the androids, who were gradually losing morale, something to fight for permanently and eventually destroy YoRHa and anyone who could refute the lie. (it is worth noting they did not come up with the idea of YoRHa, they simply hijacked it).
They witness the Pearl Harbour descent as the beginning of the 14th Machine War and remember No.2, later known as A2. Despite the heavy machine casualties they were not angry at the results.
During the events of the YoRHa boys stage play they confront Instructor Black as well as the members of the squad. Initially they come off as cold and unfeeling but over the course of the events they take pleasure in watching each of the YoRHa go insane or die and at the end even learning how to laugh.
The final stages of the plan began to form during the events of Automata. Major events include the creation of Adam and Eve, the inevitable collapse of the Forest Kingdom and Pascal's Village, the death of 2B, the destruction of YoRHa, the madness of 9S, and the creation of the Tower. Their plans hit a brief but otherwise insignificant snag as they battled A2 and their reactive evolutions took N1 and N2 on different paths of adaptations, and they fought each other. However this was shown to be temporary as they appear fine in 9S's last moments. It is revealed by the end of the game that their ultimate goal was to destroy the enemy, the androids, once and for all, but as detailed by 9S, when they saw Adam and Eve, 2B, 9S and A2 and even Pascal they had changed their minds.
The arc was supposed to be a rocket aimed for the human server on the moon, but they decided instead to simply leave, no longer held back by the need to kill their enemies, they created an arc to send themselves and the memories of the machines to a distant world.
- It is unknown what was to become of earth once the Red Girls left. Machines still controlled the rest of the planet unchallenged although now they no longer had reason to prolong the war any further.
- Even when the machine network was seemingly destroyed by A2, it doesn't translate to an android victory. The Machine Network survived losing both Adam and Eve, its managers prior and the machines still vastly outnumbered the androids. Also it isn't clear if the destruction of the network kills the Red Girls.
- It is likely the Red Girls are aware of the multiverse as Eve was seen with a tattoo of the Cult of the Watchers on his chest.
- The cinematic after the battle with Adam & Eve (Route B only)
- Beside 9S when he helps 2B against Eve (Route B only)
- Ending B
- Tower (Ending C / D)
- The Red Girl will multiply as the encounter continues, attempting to overrun the player with sheer numbers.
- While these units can be killed using normal methods, the only way to destroy them permanently is to allow the Pods to 'fracture its ego'. This is done by not killing the programs and simply waiting.
- The only attacks this unit uses are slow energy projectiles however these quickly become a problem once the program starts to multiply itself.
- Due to its gender, hairstyle and the color of clothing, as well as the tendency to shift from two female voices to a single booming male voice, the Red Girls may have some relationship to the character Manah and her ancestors the Intoners from the Drakengard franchise.
- The Red Girls make a cameo appearance in the City Ruins stage of Soulcalibur VI. They can appear behind each fighter just as the match is about to begin, or off in the distance for a few moments before flickering away.