Spine is a creature found inside the darkened Apartment 31, in the living room of the bloodsoaked false version of the neighboring apartment. Spine appears here when passing back through this area, after accessing the darkened telescope room. Spine was one of the unwitting neighbors that the Stargazer remade before the arrival of the visitor. She dwells in the Stargazer's apartment, but it has been watching Sam, entering his apartment to be close to him, and sleeping alongside him. Her presence is indicated even before she is met face to face, with messages that you feel something brush against you, warm breath on your face, or a clammy hand on your back while you are in your apartment. Spine wishes to remake Sam to be like herself, so that the two of them can be together in its home instead, where the light isn't so bright. She can likely access Sam's home and remain unseen because she inhabits a ruined, alternate version of Apartment 33 that is accessible through Apartment 31 after turning off the lights.