Duey

Also known as The Ghost, not to be confused with The Ghost (Spirit)

The blood brother who didn't survive the Battle of Train. Huey and Luey try to avenge him in the story.

Biography
Duey was born as the youngest of the three brothers. He was rambunctious and fun loving. While initially hesitant, due to looking up to his brothers, Duey joined the Hseesh Army ( ha-Zaesh ) alongside Huey and Luey. Following the Battle of Train, also known as the Great Movement, a bomb fell in between the three brothers. After waking up in a coma, Huey and Luey woke up without Duey, who was presumed dead.

King's Apprentice

As revealed in the Season 1 finale, "King Terry", Duey was not in fact dead, and kidnapped by King Terry's Army. After being forcibly possessed with a spirit only known as The Ghost, Duey, now Special Agent G, aka the Ghost, worked as a rogue assassin. Huey and Luey while attempting to call back to the brother they once knew, were defeated. Later, in the Season 2's mid-season finale episode "Kurinji", Duey killed Huey and Luey's 489 year old mentor Master Glizzard in the night.

The Prince King

In Season 2's two part finale "The Foreskin of Christ (PBUH)" The confronted King Terry was killed on his throne from Luey's sword, the Foreskin of Jesus (Rough Translation). While briefly flashing back to childhood, Duey collapsed. Waking up, The Ghost completely took over and stabbed Huey in the shoulder, took King Terry's crown and ran off.

Disappearing, Duey appeared later in Season 3, as the crowned king, but shown with signification doubts, The ghost conflicted over "taking crowns" and Duey's desires. In the final known episode, Season 3 episode 9 "Hot Beach Cutie Adventure", after the massacre of Deez, Duey was revealed to be actually the illegitimate son of Master Glizzard. It is unknown the ramifications of this, with the previous reveal of the implied reality of Master Glizzard being from the 100 years in the future

Speculation
Because of the Hydronium Scandal, it is unknown how Duey's story ended. Many theories differ. Some S3K historiographers uncovered more information from former studios that connect a much larger story involving The Ghost, and time travel.