Jenny is the ninth model of the XJ android series, but when she discovers a hidden room in her mother's basement laboratory, Jenny finally realizes she has the XJ-Sisters, which are prototypes of her. Jenny (XJ-9) is referred to as the eldest sister, despite being made as the ninth experiment. In regards to maturity and responsibility, Jenny represents the eldest sister.
Nora Wakeman admitted that she built the XJ line to replace Armaggedroid as the protectors of Earth after he had gone rogue twenty years prior.
The XJ-Sisters make their first appearances in the Season 1 episode, "Sibling Tsunami", and go on to appear in "Sister Sledgehammer", "Agent 00' Sheldon" and "Escape from Cluster Prime" (mostly cameo), and notably "Turncoats." (XJ-8 also appears briefly in "There's No Place Like Home School").
In "A Robot For All Seasons," Nora Wakeman was seen designing plans for an XJ-10 after Jenny was believed to have gone renegade due to falling under the control of Todd Sweeney. However, XJ-10 was never actually created.
List of XJ-Sister Robots
Trivia
- In the Russian version of Season 3, XJ-4, XJ-6, XJ-7, and XJ-8 were all voiced by a male actor.