You are a passenger. You are trying to get to your destination with a minimum of time and fuss. The trains are running unbearably slow today.
You are an annoying, bratty child. Run around the platform and make trouble. Poke at people. Ask questions. Fight with the other children. If your mother (with the "Mother" badge) tries to discipline, whine, wheedle, give in if necessary but then keep doing it.
(Note: there may be anywhere from two to five copies of this character in play. You're all siblings, and you passionately hate each other.)