Rhulk

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Summary
Rhulk, Disciple of the Witness is the first of the Disciples. The Disciples are extremely powerful Darkness-wielding entities that follow and take orders from the Witness. Rhulk is from the planet Lubrae and played a major role in creating the Hive by placing the Worm Gods into the servitude of the Witness. He ends up watching over the Witch Queen and the new Hive worms on Fundament from his Pyramid.

Later on, however, after Savathûn's rebirth with the Light he was trapped by a curse placed by the Witch Queen. He would retaliate by bringing the Scorn into her Throne World and commanding them. Rhulk serves as the final boss of the Vow of the Disciple Raid where he is killed by Guardians.

Personality
The Witness is the master and proclaimed savior of Rhulk. As a result, Rhulk is entirely devoted to The Witness and detests Guardians for how they use Darkness (in the form of Stasis). He believes and sees himself above all who despise him and even taunts the Guardians as they fight him. He seems to enjoy experimenting with the worm familiars, and he more than likely befriended the Worm God(s). Another notable thing is that he seems to have a low opinion of the Hive.

According to the Shattered Suns lore book, Rhulk displayed psychopathic tendencies as a young warrior. He was heartless uncaring which caused his own family to fear him. However, as a Disciple he was praised for these qualities, which likely made him egotistical. An interesting note is that Rhulk keeps honesty dear to himself. In fact, as a warrior he was confused why the Lubraean military regiment would be so honest and upfront about their misdeeds and failures. On the other hand, his parents lied about their true intentions and actions, likely causing Rhulk to appreciate honesty more and more.

Another notable thing about Rhulk is that he, even as a younger warrior, failed to plan ahead for potential threats and to outwit his enemies. It was evident he valued only strength and not scheming. Interestingly enough, he believed Savathûn would betray The Witness and told her that if she made one wrong move, he would use the Upended to destroy her entire Throne World. However, Savathûn was able to outwit him by cursing the Pyramid with Light from the Wellspring. She was even able to shut down the Upended, leaving Rhulk powerless. With him valuing strength, he did not predict the Guardians would use his own Pyramid power against him in order to kill him.

Sources:
https://www.ishtar-collective.net/categories/book-shattered-suns

https://www.ishtar-collective.net/entries/resonant-fury-cloak

https://www.ishtar-collective.net/entries/resonant-fury-mask

https://www.ishtar-collective.net/entries/resonant-fury-grips

https://www.ishtar-collective.net/entries/resonant-fury-vest

https://www.ishtar-collective.net/entries/resonant-fury-strides