While writing The Last of Us, Druckmann had a general idea of the events that would shape Ellie's identity; when conceiving the story direction for Left Behind, he found that these events were suitable.
Saat menulis The Last of Us, Druckmann memiliki gambaran umum tentang peristiwa yang akan membentuk identitas Ellie; saat hamil arah cerita untuk Left Behind, ia menemukan bahwa peristiwa ini cocok.