i think apertures core motivator in life is her desire to have control- both pre- and post-amnesia. before she lost her memory, aperture was cursed by a ritual she had no choice in partaking in and subsequently set the tone for her entire life to try and "fix" her. therefore, she had no control over the way she was treated when she was growing up, and she found that her victories were quickly turned against her as an adult too. in the end, she could never win. the only sense of control in her life was taking azraels fate into her own hands and becoming a doctor for rhodes island, helping command it.

post amnesia, aperture still desires the same control, as shes haunted by the person she used to be that she has no memory of. she doesnt want to atone or become a better person; she just wants to become someone for herself. she wants to be aperture, not lilith. as far as shes concerned, lilith is a complete stranger to her. in a way, aperture doesnt know if she should continue to say that that name is hers. is it really? all of her documents call her lilith, all of the people from her past who have come back have called her lilith, lilith is on everything that is hers

but she doesnt know this lilith. this lilith is a stranger to her. shes just a stranger walking around in lilith's skin.

she cant help but think about all the things lilith did before she woke up; all the things that she couldve done to make the vicar the way he was, all the enemies she made and the choices that led her to where she was and the things she said that made people love her or hate her. and now shes left to face the consequences of everything that lilith did. it wasnt even her who did them. how could others claim to know her better than herself? how could she even pretend to know what lilith would do or say at all?

shes a stranger in lilith's body.

so i think the control over her own identity is something thats very important to aperture. she needs to become someone who is known for being aperture, the doctor, not this person who she doesnt know at all.