The Elf king was the former ruler of the Nation of Gulfen, and Trellis's and Luger's father. He was an elderly stonekeeper completely controlled by Ikol.
The Elf King was originally a quiet boy from a small elf village, living with his brother. Some years before the books take place, he was among a group of Stonekeepers that lost control over their stones and abilities causing their minds and bodies to become possessed by their stones. The possessed stonekeepers transformed into colossal beasts that went on a rampage that ended only when members of the Guardian Council, including Emily's great-grandfather Silas Charnon, stepped in managed to subdue the beasts.
Doing so resulted in the corrupt stonekeepers' deaths, except for one. The sole exception was the future king, as the elders were able to separate him from his stone. Instead of executing him, they locked him up in solitary confinement in an attempt to cure him of his curse. While isolated, however, the boy spoke only of his desire for power, warned of dark days to come as well as telling them would regret keeping him alive, and he would show them why.
Leon Redbeard's father was a one of the guards assigned to watch over the boy's prison cell the night his stone rejoined him. The stone helped the boy escape by the means of a massive explosion, killing everyone present.
The Elf King then assumed leadership of the Elf Nation, through unexplained means. During his unnaturally long rule, the Elf King declared war on the rest of Alledia. However, none of this was through his will, as he was being controlled by Ikol the entire time as a puppet ruler.
Though the cause of the Elf King's death is unknown, he has been reanimated by his amulet and kept undead. His corpse is solely controlled by Ikol.
Book One: The Stonekeeper
The Elf King is not mentioned until the end of the book, during a battle between Emily and Trellis. Trellis attempts to convince Emily to help him in the assassination of the Elf King, however, this plan does not come to fruition.
The Elf King makes his first physical appearance when Trellis is captured and brought back to the palace after his failure to apprehend Emily. The King expresses his disappointment in Trellis's failure, and sends him out again with the assistance of Luger, the King's second-in-command. In secret, the Elf King enlists Luger to kill Trellis should the prince rebel against his father again.
The Elf King appears again as Trellis delivers a report. The king tells him that trellis failed him and he will fail him again and that he will be continuing in his mission, despite the King's order that Trellis returns. The Elf King later sends a bounty hunter, Gabilan, to kill Emily and apprehend Trellis.
The King is only briefly mentioned in The Last Council.
The Elf King summons Max to discuss about the voice of the amulet, offhandedly mentioning that he has become a fertile ground for rumors. When Max deceives the Elf King, he takes him for his word, and swears to execute all that insult his best officer. He then requests Max to finish what he set out to do: destroy the remnants of the Guardian Council.
The Elf King appears as part of a memory twice. The first time, he warns Trellis of his interest in ancient history and his idolisation of Virgil. The second time, the King interrupts one of Virgil's history lessons and detains him. Trellis tries to fight back, but the Elf King strikes him across the face and issues a Shadow, Sybrain, to Trellis.
The Elf King sends Logi and a garrison of elf soldiers to surrender themselves to Frontera's army, giving Logi a portal to the Void. Once the troops are inside the prison, it activates, creating a large explosion.
Emily later travels to the Elf King's palace and reveals to the elves that he was controlled by the Voice all along. Ikol, through the Elf King, begs Emily to lead the elves with him, but Emily refuses and institutes Trellis as the new king.
The Elf King is a tall and imposing figure, draped in a white cloak and a long neckplate with his stone set within the collarbone. His hands are clawed and can be used as a weapon.
The Elf King wears a mask that completely hides his face, apart from his long elf ears. Underneath his mask, his face has been mutated and branded with the symbol of Ikol. His facial features are completely gone, aside from his mouth.