Formerly known as Kellad, he was once a resident of the ancient kingdom Sharenian, and was the captain of the royal guard. He became the teacher of Prince Sharen IV. When King Sharen III tried to kill Sharen IV, he stopped him and saved Kellad's life. Later, Sharen III became vindictive and tried to execute him for treason, but Sharen IV was able to keep him alive and merely have him dismissed from his court. In the end, he became the commander of the Sharenian Defense Unit, a squad of knights who were rejected from becoming official Sharenian Knights for one reason or another, consisting of Hardin, Ain, Ryan, Quieg, Ed. They would spend their time training by hunting moles nearby.
After Sharen III summoned Ergoth Dunamis in response to a coup lead by his son Sharen IV, Kellad and his squad attempted to save the prince. They became trapped by Ergoth's power, being forced to relive the fall of Sharenian for centuries while attempting to break the curse, because they were devoted to their eternal pledge to Sharenian as long as a single person in their kingdom remained alive. The squad, slowly going insane, started acting different than they normally would. Hardin, always one to face his foes upfront, started attacking Ergoth's demon minions from behind. The first time they reached Ergoth, the group was able to rescue a little girl from Ergoth's demonic minions, but every subsequent repetition led to her death. Hardin, feeling incredible guilt over this along with mental fatigue, suffered hallucinations of her screams. Forced to relive the events of Sharenian's fall for centuries, the squad eventually turned on Kellad after believing that his true loyalty was to Prince Sharen IV rather than the kingdom of Sharenian. The group believed that Kellad wanted to use the Rubian, a gem said to contain the ability to revive the dead, on Sharen IV, but his subjects had other plans; Hardin wanted to revive the little girl and save her. Kellad was forced to order Quieg (who only cared about following orders and completing his mission) to kill his former comrades, and then destroyed the Rubian, revealing that it was an ordinary gem with no special powers.
Throughout these events, the White Mage disguised himself as Sharen IV and would repeatedly convince Kellad to never give up his loyalty to the prince, facilitating Kellad's insanity and turning him into an eternally loyal servant. After Kellad's group killed each other, the White Mage, still disguised, informed Kellad that centuries had passed and that the group was trapped in a parallel dimension created by Ergoth Dunamis. After escaping the parallel dimension, he defeated Ergoth Dunamis's clone for the last time and retrieving the Rubian in the real world. The White Mage infused the Rubian with the power to bring his squad back to life, provided they find new bodies to inhabit.
As Kellad relayed the story of Sharenian and the Rubian to a group of treasure-hunting explorers (Mogg the Warrior, Khalid the Magician, Juli the Bowman, Coleman the Thief, and Freya the Pirate), he presents it to them as a reward for listening to his story. Upon touching the Rubian, the souls of Kellad's former allies fuse with the group of explorers, taking over their bodies and forming new beings that would become the Elite Bosses; Hardin fused with Mogg and became Mogadin the Black Knight, Khalid fused with Ain and became Khaliain the Mad Mage, Juli fused with Ryan and became Jurai the Vicious Hunter, Coleman fused with Quieg and became CQ57 the Rampant Cyborg, Freya fused with Ed and became Freyd the Bad Brawler, and Kellad fused with the fallen clone of Ergoth to become Darknell. The new group pledged to serve the White Mage and become his eternal servants.
- 친위대장 듄켈 (Guard Captain Dunkel, Chinwidaejang Dyunkel) comes from Dunkel, which is the German word for "dark", and is also the name of several types of dark German lager.
- In KMS, "오늘 친위대장은 너희들에게 매우 실망했다." (Oneul chin-widaejang-eun neohuideul-ege maeu silmanghaetda.) ("I, the Royal Guard, am very disappointed in all of you today.") is based on a South Korean meme and famous line of the webtoon HIVE, "중대장은 너희에게 실망했다!" (Jungdaejang-eun neohuiege silmanghaetda!) ("You're all a disappointment to your company commander!" (Pay))
- Ergoth's leitmotif/theme BGM was Eregos, but in Awake update, his theme changed to SubterminalPoint, the same theme as Guard Captain Darknell.