Five and Nine grew up in the settlement together, and after Nine and Twelve escaped, Five was left behind (either of her own volition or not, it remains unclear). After becoming an FBI agent, Five appears to have taken the Sphinx case due to her knowledge of Nine and Twelve. Five also harbors a sadistic, bordering on extreme obsession with Nine that is vaguely implied to have romantic, sexual, or at least intimate undertones, as he becomes her twisted target of hope for human connection after being trapped so long in her mental cage of isolation. She is fixated on the idea of playing a "game" with Sphinx and psychologically torturing Nine however possible. She makes the purpose of her limited lifespan to find, capture, and "beat" Nine -- that is, to put him in a submissive and helpless position. To do this, she engages in multiple mind games with Nine and interrupts his plans to mess with his goals as much as she can.