Joo Dee was one of several officials of Ba Sing Se using the same name who had been brainwashed by the Dai Li to be a guide for important visitors to the city. Her robotic, cheery demeanor, mechanical mannerisms, and tendency to hold the party line when talking about the official political practices of Ba Sing Se were all the result of brainwashing by the Dai Li. In general, she existed to neutralize unwanted outside influences. Joo Dee once served as a caretaker and tour guide for Aang and his companions after their arrival in the city. She later served as Supreme Bureaucratic Administrator to the city, a position that was created after the Fire Nation's coup.
This Joo Dee first appeared to be a stereotypically vapid and ignorant tour guide. Despite the fact that Team Avatar had information regarding the war against the Fire Nation, she constantly "handled" the entire group into following her tour, promising them an audience with the Earth King within six to eight weeks. She showed no change in personality when Team Avatar responded negatively to her bad news and was constantly smiling, giving her a somewhat eerie demeanor. When Aang and the group went searching for Appa and information about the war, Joo Dee hung back from the others, ever-smiling. When Sokka asked a question that got close to the truth, Joo Dee would smile broadly and shake her head at the person under interrogation, eliciting a withdrawn, scared reaction from him or her. When Team Avatar crashed the Earth King's party, Joo Dee urged them to leave lest they would all be in trouble. She attempted to usher them out, but by doing so, she inadvertently caused Aang to spill the contents of the jug he was carrying over one of the noble women and subsequently exposed himself as the Avatar. When all the party guests became aware of Aang's presence, Joo Dee's perpetual smile melted into something closer to despair and fear.
After meeting with Long Feng, Aang and company were to be escorted home by Joo Dee, but they were shocked to see a different woman with the same name and eerie smile who claimed to be Joo Dee in place of the Joo Dee they had initially met. The original Joo Dee reappeared later, claiming her disappearance was because she took a vacation to Lake Laogai. When her efforts to prevent Aang and his friends from searching for Appa failed, she was seen distraught before Long Feng, one of the few times she showed emotion, with the exception of happiness. Long Feng was then seen hypnotizing her. Later, Team Avatar discovered that the Dai Li brainwashed many women into becoming Joo Dees, and may have considered them to be interchangeable.
Following the Coup of Ba Sing Se and her imminent return to the Fire Nation, Azula placed one of the Joo Dees in charge of Ba Sing Se as Supreme Bureaucratic Administrator. According to the princess, she was the "perfect" person for the job.
Joo Dee's design and personality was based on Miken Wong, the line producer for the show.
The concept of handling visitors and denying any negative events to the general populace are similar to the workings of the real-world nation of China, which Ba Sing Se is based upon.
In a real-world parallel, North Korea requires that all foreign visitors to Pyongyang be tended to by state guides at all times.
Joo Dee sounds rather similar to Judy and is possibly a reference to the common name. It also brings to mind the name Judas. In shepherding, a Judas is a goat who has been trained to lead sheep and cattle from one place to another, such as grazing fields, pens, slaughter, etc. If the Judas proves ineffective at leading other livestock, it is slaughtered.
Joo Dee, in China, is the equivalent of "Jane Doe"; this fits the fact that the Joo Dees lack identity and are so alike.
Joo Dee did once show signs of free will when talking to Long Feng regarding her failure to handle Team Avatar. She attempted to explain that she could not work well under the conditions, meaning that she possibly took the job of her own free will, though it was revealed that she had been brainwashed like the other Joo Dees, as Long Feng was able to convince her to continue taking charge of Team Avatar, utilizing a code phrase.