House and Masters
House sees Masters as his younger self. He relates to her almost instantly.
House always had morals and was always very sensitive, he got "corrupted" throughout the years because he's a doctor and because he's in pain. It screwed him up. His morals changed and twisted, results meant everything no matter what, Everything to solve the puzzle/save lives.
House notice Masters gift immediately. It makes him feel threatened and at the same time overprotective of her. Threatened because it makes him feel replaceable, and overprotective because he doesn't want her to end up like him. She is very similar to him: pragmatic, anti social and an exceptionally good doctor.
At the end she leaves her calling because she doesn't compromise her morals. Unlike house she completely listens to her "irrational" side as house would phrase it, and leaves the hospital.
What an amazing character