 Before Portal , Aperture Science conducted experiments to determine whether human subjects could safely navigate dangerous " test chambers " , until the artificial intelligence GLaDOS , governing the laboratory , killed its employees . At the end of the first game the protagonist Chell destroys GLaDOS and momentarily escapes the facility , but is dragged back inside by an unseen figure later identified by writer Erik Wolpaw as the " Party Escort Bot " . A promotional comic shows estranged Aperture Science employee Doug <unk> , who used graffiti to guide the player in Portal , placing Chell into suspended animation to save her life , until the beginning of Portal 2 . 
