Most of you probably know this, but I thought of mentioning it anyways. I have two of the pets cheats in a userstartup.cheat file and that is how I worked this one out.
I was playing my game and got a room mate, I was so dissapointed when I saw that now I had an extra person to care for, because I could tell her what to do and see her needs and cancel her actions. Then I remembered my userstartup cheat file and removed the pets cheats and now she is a npc doing random things and caring for herself

These are the cheats that I used to have (I love the randomness of the room mates )
boolprop petactioncancel true
boolprop controlpets on