Change Their Lives

    Earlier, I was thinking about a particular series I like--thinking about what exactly makes it so awesome. And one of the things I thought made the story great is how the main character changes the lives of others around him.
    An inner change (also called character development) in the main character is important. But I think that it's also really great for a story when the main character changes other character's lives (or their day, depending on just how major or minor they are). It's a beautiful touch for a story, it can change the main character him/herself, and it can get the main character new allies--or new enemies. Having the main character's life collide with another character's creates a plot thread, and/or more conflict--which can be great for a story.
    Do your main characters change other character's lives?