Our theory is that Chelle, though she acts like an android, is actually human. This long exposure of being treated like a test subject and lack of human contact has caused Chelle to revert to robotic behavior. She doesn't respond when GLaDos interacts with her. She shows no emotion when GLaDos tells Chelle that she "validates [Chelle's] parents' decision to abandon her." On the other hand, GLaDos shows many human characteristics.In Portal 2 GLaDos harbors resentment towards Chelle for killing her in Portal 1. She expresses her feelings towards Chelle with constant sarcasm, ridicule, and intentional deceit. GLaDos is constantly taunting her and trying to draw a reaction out of Chelle. At one point, GLaDos asks Chelle if she smells that and continues to tell her "that is the stench of my utter disappointment in you." Phrases such as this blatantly express GLaDos's distaste and resentment towards Chelle and other humans.