Can you share examples of unplanned characters in famous books or movies that ended up becoming essential to the story?

Why do people tell me that I obsess over my weight when really what I'm doing is caring about is my health so that I wont have health problems? I feel like they don't care about me, the way I look or just want to gamble with my health.
What other public assistance programs have been successful in helping disabled and senior citizens lead a dignified and independent life, without depending on anyone?