Ellie first met Carl as a child when he wandered into her clubhouse. The two became close friends after realizing they shared a similar admiration for explorer Charles Muntz (who later in the movie becomes the main antagonist). Ellie made promises with Carl by saying "Cross your heart?".
Eventually, Carl and Ellie were married, but were unable to have children. They constantly tried to arrange a trip to Paradise Falls, but every time something always happened to prevent it. After Carl finally managed to acquire a ticket, Ellie died of old age.