He worries about his sister. Why she won't play with him. He worries about his brother. The brother that fights him on everything seems to be too lethargic to fight back and gives him whatever he wants, however much Muffin pushes his buttons.
So he goes around with a stethoscope and his 'doctor' box. He listens to Jordan's chest and when she says her tummy hurts, he listens to that too. He gives Evan an injection but before he does so, he tells him "Kor Kor, don't cry. Is good for you. Make you feel better. I not putting anything in your bum bum" (The boy remembers all too well the medicine that got shoved up his bum rather unceremoniously.)
It's nice to see him all concerned even though they fight like cats most of the time. Grandma commented that he 'could' become a doctor. Okay, if he wanted to but the hours and grunge work suck and if a patient threw up in front of him, he would join the patient, gag and throw up too. And of course, his bedside manner would need work, especially if he roared at patients. But I'm not going to push it.