You wouldn't think it possible to be isolated in a city of over 2 million people, but probably about 1.9 million of those people feel lonely at some point or another. Almost all of the characters in Amélie radiate a sort of loneliness—whether it's Dufayel and his fragile bones, Georgette and her hypochondria, or Amélie's dad and his lost gnome. What Amélie does, through her good deeds, is bring people together. She even finds someone herself in the end, which makes her just a little less lonely, too.
Questions About Isolation
Does Amélie feel lonely when she's alone? What's the difference between being lonely and being alone? What makes Amélie start to feel lonely?
How does Dufayel cope with being shut off from the outside world? What does he do to experience things that he cannot? How does Amélie assist him?
In what ways does loneliness manifest itself in other characters? Are there any characters who don't seem lonely?
Chew on This
Even though Amélie does good deeds for other people, she's still lonely because she doesn't actually interact with them. Many of them have no idea who their "guardian angel" is.
In order to do a good deed, Amélie has to figure out what the other person most needs. When she figures out she's lonely, the greatest good deed she can do for herself is find the right person to be with.