Nat is intensely curious with Jacks biology, given that he's a genisae turned vampire and has some unique abilities due to his former species. She doesn't have any real feelings other than that towards him, viewing him as a means to an end.
Jack is frightened of the doctor to a serious degree, almost to the point of panic attacks when she's around. He submits himself unwillingly to her experiments and allows himself to be prodded and poked in Nat's endless persute of knowledge.
Nat is intensely interested in Pach, to the point of obsession with their born with abilities. They're trying to use them to open the gate to new worlds.
Pach despises the doctor, smart enough to know that she doesn't mean well at all. They don't like the pills and experimentation and they don't take kindly too it, one of the roudiest patients at the Wellness Clinic.
Nat looks down on Cain in a rather snooty manner, not maliciously or anything but just because he's a younger doctor and she considers herself to be quite important in the wellness clinic. She doesn't mind his presence and harbours feelings as close to affection as she can muster in private.