PersonalityEdit
Official character description for PK would mark her down as a cold and solitary person, PK dislikes chit chat, she only likes those who can match her in terms of strength. Compared to many T-dolls in Girls Frontline, PK is one of the less friendly one to the Commander, her speeches/replies are short and simple, she does not wish to have excessive social interactions with anyone.
Though her post OATH comment would suggest that she accepted that the Commander is also a creature of solitude just like her, she is finally able to find another who she could truly rely on and thus lowered her wall.
Being a product derived from PK, MG PKP
PKP 
would be PK's little sister, some of PKP's quotes mentions PK. Also being a product derived from PK, MG AEK-999 AEK-999 
doesn't mention anything of this sort.