Yu was part of the delegation that was sent by the System Lords to negotiate Earth's entry into the Asgard's Protected Planets Treaty, along with Cronus and Nirrti. He partially favored the treaty, as his interests no longer resided in that area of the Milky Way, looking toward other exploits. After SG-1 revealed Nirrti's treachery to kill Cronus, Yu was convinced to allow Earth into the treaty, and also let them keep their Stargates, which were originally to be forfeited as a condition of the treaty, although he and Cronus did note that any SG-teams found on Goa'uld-controlled planets would still be fair game. (SG1: "Fair Game")
During the aftermath of the deaths of Apophis, Cronus and Heru'ur, Yu was among the System Lords who engaged in combat with the others to come to dominate the power vacuum. He made strides against Olokun, but soon began to suffer attacks by an unknown adversary. When the System Lords gathered to end the conflict, Osiris - who recently gained the respect of the Goa'uld - arrived as an emissary on behalf of Anubis, whom he revealed to be the one behind the attacks. Yu was the only one of the seven System Lords present who voted against Anubis's regain of his former rank of System Lord, and was the only one among the High Council of System Lords that had originally banished him in the first place. Dr. Daniel Jackson - posing as his lo'taur Jarren - attempted to use Yu's Tel'tak to kidnap Osiris in order to free his host, Sarah Gardner, but Yu stumbled upon them. Osiris stabbed Yu with a knife, but Yu survived and declared war on Anubis. (SG1: "Summit", "Last Stand")
When Teal'c lead a raid on P3X-042, his Jaffa captured Teal'c. Noting that Teal'c was not one to blindly follow another, Yu allowed him to leave unharmed after he revealed the treachery of K'tano, the new leader of the Jaffa Rebellion, inspiring Teal'c to challenge K'tano in Joma Secu, resulting in him learning that K'tano was actually Imhotep. (SG1: "The Warrior")
When Colonel Jack O'Neill was captured by Ba'al and taken to his secret fortress, the SGC contacted Yu with information about it, knowing that he would attack the fortress as Ba'al was hiding it and his anti-gravity research from the other Goa'uld. In the message, they asked Yu to target the power generators first so that O'Neill could escape. Yu sent his Ha'tak to the fortress, bombarding it from orbit and knocking out the power generators first as asked. O'Neill escaped thanks to Yu's attack and Ba'al abandoned the fortress which was left heavily damaged until SG-1 returned for a raid a year later in which it was destroyed. (SG1: "Abyss", "A Matter of Honor")
Yu then spent the next year fiercely campaigning against Anubis, and finally managed to rally the other System Lords against him. However, the power of the sarcophagus was beginning to fail to fully restore him, until he reached the point where he was no longer able to take a new host. Yu began to suffer from a sense of senility, giving blatantly foolish orders that could jeopardise the campaign against Anubis. In turn, his First Prime Oshu had to take control of his master's Empire to keep it from falling into anarchy, and when Ba'al took leadership of the United Alliance of System Lords, Oshu agreed to obey Ba'al so long as his actions lead to the destruction of Anubis and the betterment of his master's territory. (SG1: "Full Circle", "Fallen", "Homecoming", "Orpheus")
When Ba'al took control of the Kull warriors, Yu was accompanied by Camulus, Amaterasu and his First Prime in a second delegation to Earth to seek their help in defeating Ba'al. Yu and Amaterasu left empty handed, while Camulus sought asylum. (SG1: "New Order, Part 1", "New Order, Part 2")
Over the next year, Amaterasu and Yu campaigned against Ba'al, while the rest of the System Lords fell, fled, or surrendered. At a meeting in the Hasara space station, Ba'al sent his underlord Selkhet to negotiate their surrender. Replicator Carter arrived, posing as Samantha Carter, and ran a blade through Yu's chest, finally killing him. (SG1: "It's Good to Be King", "Reckoning, Part 1")
- In an alternate timeline in which Stargate Command never existed, Yu was one of many Goa'uld who allied under the banner of the Sovereign Ba'al and fought against the resisting System Lords. In 2009, he was promised a domain on Earth by Lord Ba'al upon the successful conquest of the planet. (SG1: "Continuum")
- Yu was the only System Lord to act as a representative on both committees to Earth.
- Yu was the only Goa'uld who voted against Anubis's return.
- Yu, Apep and Apophis are the only System Lords to not be named after a god of sorts. Yu is named after an emperor and Apophis/Apep is the Egyptian chaos embodiment.
Unlike most Goa'uld, who are generally megalomaniacal and obsessed with total domination, Yu can be fairly pragmatic and methodical. While certainly no friend of Earth, Yu is mostly concerned with strengthening his hold on the territory he already controls, while other Goa'uld will often haphazardly waste resources trying to conquer the entire galaxy.
Yu is also often fairly willing to negotiate with Earth (as opposed to other System Lords which view all humans as just livestock) and achieve a diplomatic solution more or less co-existent with the Tau'ri, twice assisting them in their campaigns against other System Lords when their own forces were insufficient to the task at hand. However, it is stated that this is due in no small part to the fact that the territories Yu controls are on the opposite side of the Milky Way Galaxy, and thus most of the other System Lords are located between Yu and Earth: allowing Earth to survive helps destabilize Yu's Goa'uld enemies located between the two.
Another factor is simply the persona that Yu took, that of one of China's early emperors, who was not really considered a "god" per se. Like many other Goa'uld, however, Yu does generally seem to believe his own propaganda (unlike Ba'al, who privately acknowledged the falsehood of this claim and was rather flippant about it). Still, Yu rarely asserts this fact, even when questioned, or endeavor to force others to acknowledge it (as opposed to Apophis and Sokar, who were rather self-obsessed with their status as "gods").
Unlike other Goa'uld, who might agree to an alliance with the Tau'ri to achieve an immediate goal and then turn against them when the time is right, Yu is generally shown to keep his word and stick to their agreement; the only time he "betrayed" Earth was when his senility caused him to make a mistake. Also, unlike other Goa'uld, who will attempt to exploit any chance to kill the shol'va Teal'c and only fail to do so when Teal'c escapes or kills them himself, Yu once allowed Teal'c to live even after K'tano had attempted to convince Teal'c to assassinate him, Yu implying that he admired Teal'c's ability not to blindly serve another (Although it should be noted that his actions also undermined Imhotep's attempt to infiltrate the Jaffa Rebellion, suggesting that Yu's true goal was to defeat his adversary while saving face).
As he became increasingly senile, Yu's orders became more erratic and unreliable, but his past actions ensured the continued loyalty of his First Prime, Oshu, who took control of Yu's armies while leaving his master as a public figurehead, agreeing to serve the more mentally stable Ba'al so long as Ba'al's actions would serve to benefit Yu, such as through ensuring the destruction of Anubis.
Behind the scenesEdit
Two references in the series to the historical basis of Yu show a clear contradiction on the persona Yu assumed. In a briefing at the SGC, Daniel Jackson introduced Yu as "Yu the Great. He did not assume the role of a god, per se. But may have been one of China's earliest emperors... He founded the first recorded dynasty". (SG1: "Fair Game") Later, Jackson, impersonating Yu's servant, announced Yu's full title as "the Jade Emperor, the exalted Lord Yuhuang Shangti". (SG1: "Summit") The first reference refers to Yu the Great, founder of the Xia Dynasty, a mortal who lived in the 21st century BC, and "Yu" would be written as 禹 in Chinese. The second reference refers to the Jade Emperor, a deity of Taoism developed much later on, and "Yu" would be written as 玉 in Chinese(pronounced as Yù).
It is possible, however, that Yu assumed both personae at different times.
His Jaffa symbol is similar to the Chinese character 中 (zhong) which is translated as "middle", and is used in the Chinese word for China ("zhong guo"; lit. "middle Kingdom", or "land in the center of all things").
Yu wears Qing-era attire, which was not introduced to China until the 17th century AD. To be fair, however, nobody is quite sure what Xia-era attire would have looked like.
His full name Yu Huang Shang Ti would in Chinese be 玉皇上帝 (Pinyin: Yù Huáng Shàng Dì), meaning "Jade Emperor God".
While it is never stated on the show, it is possible that China's traditional association of Chinese emperors with dragons was originated (in-universe) by Yu, as Goa'uld symbiotes possess a decidedly serpentine appearance. What is more, the traditional Chinese dragon, unlike the Western kind, is wingless, has a snake-like lower body, and its head is often flanked by exaggerated "ears" reminiscent of Goa'uld head-fins.