He really cares about his patients and wants to help them o a personal level. They are not just a paycheck to him. He takes time to care for each patient however they may need, even if it takes time out of his personal life, and even if he has to form a close bond with the patient in order to benefit them.
I have a soft spot in my heart for this character. That scene where she briefly appeared in the background was so sad---the nurse appeared to be congratulating her, and then Winona runs by barking, and Screw Loose gets a terrified "It wasn't me!" look on her face. And this pic is so lovely.
Doctor Sun was probably the kindest to Screw Loose in the whole hospital. He would feed her, and help her to feel welcome. Sometimes Doctor Sun would feed her biscuits! One day, when he was feeding her some vegetables, he said; "Good girl, Screw Loose!" It made Screw Loose feel so special. She had never been told that before. She barked at him. "You'll have to learn english, my dear." Sun said sympethetically. Screw Loose's smile faded. She had been told to speak English all day. For the rest of the meal, Screw Loose was quiet.