For more details on the deep lore and character backstories, you can explore the NieR:Automata Wiki .
As they hunt down the "Red Girl" entity and the twin leaders , 2B is forced to kill 9S several times to prevent his data from being corrupted, a tragic secret she carries as part of her "Executioner" (2E) programming. The Terrible Truth NieR.Automata.Game.of.the.YoRHa.Edition-CODEX.p...
Witnessing this from afar, 9S descends into a vengeful madness. He discovers the horrifying truth behind the war: They died out thousands of years ago. For more details on the deep lore and