The Failed Vessel and The Pale King
The failed vessel was the very first vessel ever created by the Pale King and White Lady. His birth is slightly different from the other vessels as he has a biological sex, male, and a bit less void than the others. At first he seemed to be just like any other vessel but his imperfections became more obviously when he grew up.
Before he was replaced with the Pure Vessel the pale king raised him from infancy, believing he would be able to stop the infection and save everyone. The young vessel was treated in a similar fashion to the Pure Vessel and as he grew he became very attached and loving to the Pale King, believing the King loved him back.
Even after he was replaced and handed over to the Soul Master to be used for experiments he still loved his father, but wondered why he’d abandoned him to such a horrible fate. This also stirred a burning hatred for the Pure Vessel and other vessels afterward, leaving him to believe they all exist to replace him.
His delusions have let him to kill any vessels he came across and ensuring the seal on the Black Egg was broken, proving to his father that he was the one who should have been used to seal the Radiance and not the others, as he believes he is the only pure one and the others are failures, not him.
If Ghost were to Dreamnail the Failed Vessel, he would find himself in a corrupted version of the White Palace, with a glowing form of the Radiance seen in the background clouds, entering the tower would take him into a short hall with the Pure Vessel hanging from thorns from the ceiling, and the main area where he would find the Pale King on his throne wrapped up in thorny vines. Each image symbolizing something in the Failed Vessel’s mind.
Radiance being Freedom, Hung Pure Vessel being Revenge, and the imprisoned Pale King being Desire.
It would seem strange that after all he’s been through he would still love his father but he does, in a slightly perverted sense of the word. He refuses to accept the King never really cared for him and will not tolerate anyone speaking badly about him. He just wants to prove himself to the Pale King, that he’s not a failure and wants him to be proud of him.