Character Analysis
Sister, Sister
Pris doesn't want to move in with Isidore because the "'chickenhead'" likes her, and she finds the idea all kinds of icky (14.36). So, we're going to go with a diagnosis of severe self-loathing issues. She tells Isidore that the Chablis and fresh fruit are wasted on her, signaling that she believes she doesn't deserve such special treatment as she is an android (13.11).
You know what they say: you have to love yourself, first.
The Odd Couple
As an android, Pris lacks empathy. She only concerns herself with her own problems and is unable to understand the emotions of others—like in the key scene when the androids are voting about whether to stay in the apartment and what to do with Isidore. Pris votes they stay in the apartment:
I think J.R.'s value to us outweighs his danger, that of his knowing. Obviously we can't live among humans without being discovered; that's what killed Polokov and Garland and Luba and Anders. That's what killed all of them. (15.4)
Notice how Isidore's safety and feelings don't factor into Pris's argument? Instead, it's about what is best for the androids, where the emotion-free calculation says the dangers will be fewer for her. Even Isidore spots this fact. Although he thinks Pris is the closest to natural of the androids, he finds "a peculiar and malign abstractness pervade[ing] their mental processes" (14.21).
Or take the moment when she disfigures the poor spider despite Isidore's protests:
"Please," Isidore said.
Pris glanced up inquiringly. "Is it worth something?"
"Don't mutilate it," he said wheezingly. Imploringly.
With the scissors, Pris snapped off one of the spider's legs. (18.31-34)
Unable to comprehend how her actions will hurt both the spider and Isidore, Pris approaches the dismemberment with all the scientific composure of a future serial killer... and it leads to her death.
When Rick arrives in the apartment building, she and the other androids send Isidore to deal with him. She implores him: "Don't let him in, J.R. Say anything; do anything that will stop him. Do you know what a bounty hunger would do let loose in here? Do you understand what he would do to us?" (19.3). She doesn't care what might happen to Isidore; she can literally only think about the world in terms of how they might affect her.
Pris's concern is with Pris, period. When she finally does confront Rick, she's pushed Isidore so far away that he isn't with her, and she dies as she lived. Alone.