Basically, this is when a character gets an illness (in most cases, a cold) or an injury. Another character spends most of the episode nursing him back to health. By the end of the episode, the "patient" got over his illness, but realizes The Caretaker has caught the illness from him. He decides to take care of the now "patient". This can be Truth in Television In many families with small children and a stay-at-home parent. It's not rare for the stay-at-home parent to get an infection from the kids before the parent who works outside the house. A typical ending of the Sick Episode.