In 44 ABY, Sith Saber Gavar Khai developed the Jedi Queen project, which involved the assassination of Hapan Queen Mother Tenel Ka Djo in order to prevent the birth of an influential galactic queen of Jedi descent. Charged with the mission, Saber Querdan Dei pursued the Hapan queen to the planet Klatooine, but was ultimately slain in lightsaber combat with Jedi Knight Leia Organa Solo.
In 44 ABY, High Lord Sarasu Taalon of the Lost Tribe of Sith experienced a vision of a young Human queen, one who ruled the galaxy in the name of the Jedi Knights. Taalon became obsessed with the prevention of a galactic throne upon which sat a Jedi sovereign, but he was killed in battle before his plan could come to fruition. Sith Saber Gavar Khai, who had frequently served with Taalon during the Sith's recent battles with the Jedi, became equally determined to act in his late commander's stead. he labeled the mission the Jedi Queen project, and the Sith ultimately discovered that Hapan Queen Mother Tenel Ka Djo's appearance was similar to that of the future Jedi queen's, and they feared that Djo would give birth to the queen. Unbeknownst to the Sith, she already had a daughter—Allana Solo, disguised as "Amelia," the adopted daughter of pilot Han Solo and his wife, Leia. Hoping to prevent a future that had in reality already come to be, Khai charged Sith Saber Querdan Dei with the assassination of Djo.
Allana Solo, the target
Aboard an EE-104 Fisheye called Cryptic Warning, Dei and his crew—Hara, Sazat, and Dei's son, Fardan—ventured to the Hapes Consortium, with instructions to gain access to and kill the Queen Mother. The Sith detected a fleet of Hapan Battle Dragons heading for the planet Klatooine with Tenel Ka Djo on board. Querdan Dei and his crew followed the vessels to Klatooine, where they also found that the Millennium Falcon had landed. Observation of the camp on Klatooine revealed that it was an unofficial mission for negotiations after the planet's recent uprising against their former Hutt masters. Dei performed some reconnaissance around the camp and formulated a plan to carry out his mission.
Dei captured one of the Solo family's droids, C-3PO, and planted a bomb inside of him. Dei then paid a 2-1B surgical droid that was part of a droid's rights group to take C-3PO and pretend that it had captured the Solos' droid. The Solos' supposedly adopted daughter, Amelia, found the droid and rescued it from the droid's rights group, then took it with her to assist Djo with translation. Dei planned to activate the droid once it was close enough to Djo, but as he waited, he determined that Amelia could in fact be Djo's daughter, as she was very similar in appearance. Dei resolved to kill Amelia as well, and when C-3PO was in position, he reached for his controller to activate the bomb in the droid. However, Amelia had sneaked up behind him and taken the remote. Dei demanded that she give it back, and although she refused, he was able to determine that Djo was indeed Amelia's mother.
The Sith Saber charged the young Amelia with his lightsaber, but before he could harm her he was intercepted by the girl's pet nexu, Anji. Anji ripped out his eye before he was able to throw the nexu off of him, and as he prepared to renew his attack on Amelia, he found himself face-to-face instead with Leia Solo. She requested Dei's surrender, but he refused, and they engaged in lightsaber combat. The duel lasted for several minutes, but eventually Dei spun in such a way that he lost sight of Solo due to his newly-lost eye, and she killed him.
Soon afterward, a larger Sith force under the command of Gavar Khai failed in their mission to capture the powerful dark side entity Abeloth on the planet Nam Chorios. Abeloth contacted Khai after the battle to form an alliance against their mutual enemy, the Jedi. Khai agreed, although Abeloth soon afterward betrayed the Sith and destroyed their capital city, Tahv. Khai fell under Abeloth's influence, however, and left the Sith, joining the entity's forces instead. Although Khai still showed interest in preventing the Jedi queen from coming to be, Abeloth refused to allow him to continue the Jedi Queen project.
The groundwork for the Jedi Queen project was initially laid down in author Troy Denning's Fate of the Jedi: Vortex, the sixth novel in the nine-part Fate of the Jedi series, wherein Taalon had his vision of the Jedi queen and was later killed. The project was first named and carried out in Aaron Allston's Fate of the Jedi: Conviction, the seventh novel of the series. The project was only mentioned in the eighth novel, Christie Golden's Fate of the Jedi: Ascension, wherein it was officially cancelled by Abeloth.