Ellie was Carl's childhood sweetheart and wife. Her idol (along with Carl) was Charles F. Muntz. Her life with Carl and subsequent death were what inspired Carl to embark on his adventure in the film.
In her youth (age 8), Ellie met Carl (who was 9) and they instantly became best friends; she passionately shared with him her dreams of travelling to South America, along with her desire to move her clubhouse -- an abandoned house in the neighborhood -- to a cliff overlooking Paradise Falls, making Carl promise to help her; a moment that left a deep and lasting impression on him.
Years later, Ellie and Carl (as young adults) marry and decide to turn their old clubhouse into their new home. Shortly after they become employees of the local zoo (a zookeeper and a balloon salesman respectively) to make a living. Their marriage is a happy and loving one, and they look forward to starting a family together, but Ellie's pregnancy fails, leaving Ellie distraught. To try to cheer her up, Carl shows her their old Adventure Book to remind her of the childhood promise that brought them together, which quickly brings her out of her depression. Over the following years, they plan to save up for a trip to Paradise Falls, but they are outdone by several other pressing needs in their lives such as bills, accidents, car repairs and medical expenses.
Ellie eventually forgot about Carl's promise as their marriage continued to flourish blissfully into old age. Then one day while out on another picnic with her husband (who was planning to surprise her with the plane tickets he had bought), she collapsed from illness and became hospitalized. Before passing away, she gave Carl her old Adventure Book, but she was unable to tell him of its true meaning (possibly due to infirmity). Her funeral was held in the same church where she and Carl had their wedding.
Unbeknownst to her husband, Ellie had added photos of their happy life together in the Adventure Book and a final message saying: "Thanks for the adventure - now go have a new one!" It is only near the end of the film - after mourning her for several years - does Carl finally come across the new content, reinvigorating him at last.
- Ellie has full speaking lines during her childhood years, but has no dialogue in her depicted adult years.
- Ellie's name is based off her voice actor, Elie Docter, Pete Docter's daughter.
- In Toy Story 3, a signature of Carl and Ellie Fredricksen was seen in Andy's room.
- Ellie has her own musical theme composed by Michael Giacchino that's first heard when she and Carl meet as children and plays several times throughout Up after her death, particularly when Carl gets the house up in the air with the balloons and during the climactic battle between Carl and Muntz as it plays against Muntz's theme.
- The balloon with a stick, which is the same one that Carl got, resembles the balloon (nicknamed "Balloon") from the Winnie the Pooh franchise.