In the early 21st century, the Ulian robots were created to protect Princess Cilia during the Ulian Empire's war with the Quintani. Despite this, the ship disappeared in the Sol system. The robots were able to able to find the abandoned ship, but encountered the Tenth Doctor there, who had also tracked the distress signal. The robots attacked him, believing him to be an enemy.
Using the ship, the robots were able to track the Princess further, but were only able to tell that she was somewhere on Earth and nearby a Christmas tree. In order to find her, they shrunk robots with transmat guns to 6 inches tall, wrapped them in packages and delivered them to all the houses. The plan was that they would activate when exposed to alien technology, but would otherwise look like toys. The plan was disrupted when the Doctor was also shrunk and delivered, and his box opened by Mason Valentin. During his investigations, the Doctor's sonic screwdriver activated a robot. Though he was able to shut it off, it was after Ana Comparetto, a human, was transmatted to the ship.
Though the robots originally believed that they had found the Princess, the Doctor was able to convince them that they made a mistake and that they needed his help. He was returned to his normal size and allowed to track the Princess. The Doctor was able to convince the Princess to return, and the robot agent in the house returned her to the ship. (PROSE: The Doctor on My Shoulder)