NieR:Automata: Why did 2B keep killing 9S?

2B’s hidden designation explains an assignment. It does not, by itself, explain everything she knows.

Near the end of NieR:Automata, A2 tells 9S that 2B’s official designation is 2E: an execution model concealed behind a combat designation. His advanced abilities made his eventual discovery of the truth a foreseeable risk. The partner fighting beside him also had the role of killing him when he crossed that boundary.

That revelation answers why 2B repeatedly killed 9S. To understand what the repetition costs them, however, it helps to return to an earlier conversation about an incomplete memory backup.

2B in front and 9S behind her. This official promotional screenshot identifies the companions; it does not depict an execution. © SQUARE ENIX. Image source ↗

What A2 actually reveals

In the Tower confrontation, A2 says that 2B hated repeatedly killing 9S. She then explains that the high-end 9S model was expected to discover the truth, identifies 2B as Number 2, Type E, and describes E models as a class designed to execute YoRHa units. These are A2’s statements to 9S in the game, rather than a theory inferred from the letter in 2B’s name.

The apparent contradiction is built into the assignment. Being his partner did not prevent her from also being his executioner. The late revelation tells us that the deaths belong to a repeated relationship, rather than a tragedy that begins with the player’s first view of the pair.

It also has limits. Identifying 2B’s execution role does not establish the immediate cause of every on-screen death, an exact number of earlier executions, or the precise contents of everyone’s memory on every occasion. Those claims would need their own evidence.

A replacement body is not a complete reunion

After the prologue, 9S explains a very specific gap. He probably only had time to back up 2B’s memories; his own remain intact only until just before their rendezvous. The two characters are present again, but they have not recovered the same stretch of their shared experience.

The two adjacent lines in their reunion conversation matter together. One concerns the backup he could make for her. The other identifies the cutoff in his own memory. A restored body can therefore return without the most recent experiences that made this meeting meaningful to the other person.

The word “probably” matters too. This is 9S explaining that reunion, not a technical guarantee that every death always produces the same result. Nor does this one conversation prove that 2B retains every memory through every earlier execution. It gives us a concrete example of the distinction: survival of a model and continuity of shared experience are different things.

That distinction makes the execution cycle more painful than an endlessly repairable body suggests. Meeting 9S again is not an assurance that she will meet someone who shares all the time they have just spent together. The prospect of his return does not erase the loss.

A shared view of the city, used as relationship context rather than evidence of a backup or an earlier execution. © SQUARE ENIX. Image source ↗

The assignment is not a map of her knowledge

It is tempting to compress the reveal into a larger claim: 2B was an executioner, so she must already have known every secret about humanity and YoRHa. The cited Tower dialogue does not establish that. It connects her real model type with the risk of 9S discovering the truth; it does not inventory everything she understands about the underlying plan.

The opposite absolute would be just as careless. These lines do not prove that she knows nothing. They establish her concealed role and, through A2’s explicit statement, her distress at repeatedly carrying it out. The extent of her knowledge about a separate secret needs a separate source.

Her emotional distance can be read in that light. A2 expressly says she hated the repeated killing. Set beside the prologue’s unequal memories, her restraint is compatible with the pain of becoming close to someone she may have to lose again. That is a character reading grounded in the two scenes, not a transcript of every unshown thought or an excuse that removes her actions from the story.

The name 2E changes the meaning of the companionship we have watched. The person protecting 9S was also assigned to end his life. Even in a world where a body can return, the time two people built together is not guaranteed to return with it.