Thriaf was the Sylvan-classed son of Ratiph and a dryad. He was born on Sapience, and lived the first few years with his parents in his father's grove. However, during a lightning storm, a fire broke out in which his mother perished. Thriaf and his father moved to the forests of Ulangi, where Thriaf lived until young adulthood. During this time, perhaps as a result of his mother's death, he was prone to sudden releases of elemental fire, followed immediately by blackouts. It was in one of these subconscious breakdowns that he unwittingly killed his father. So traumatised was he that his mind blocked all memory of the event, creating false images in its place. Shortly thereafter, he travelled to Sapience to claim a grove of his own.
Thriaf was later found in a massive fire within the Eastern Ithmia, burnt and severely wounded, by the Silver Dragon Aztecia. She carried him back to the village of Eleusis, where his wounds were slowly tended to by the Atavian Muria. It was only then, after his wounds had healed sufficiently, that he was able to speak. The trauma of late had blocked out much from the young man's mind. According to Thriaf, he did not have a mother, and his father's name was only "Dad." He did, however, reveal that he had lived on an island.
The Sylvan Skye and the Sentinel Xel travelled to Ulangi, where the ferryman Giorian admitted that he was a long-time drinking buddy of Thriaf's father, whom he referred to as Ratiph. Searching further into Ulangi's cloud forest, the two forestals discovered the charred remains of a middle-aged man in a place that the ferryman confirmed as Ratiph's former grove. While Giorian could not identify the corpse, its location, coupled with the disappearance of Ratiph some time before, confirmed that it was indeed Thriaf's father.
Upon their return to Muria's treehouse in Eleusis, Skye and Xel learned that Muria had incitizened Thriaf as a formal member of Eleusis. As he daydreamed, a vivid illusion formed before them of a grove with three willow trees by a pond, and of his mother. As he snapped out of his reverie, the two asked him of what they had seen. Not realising he had conjured an illusion, he became panicked at what he saw as insanity, and in an instant fires sprung to life in the room. When it was pointed out that he started the fires, this only frightened and confused him further. Muria became agitated, having witnessed the illusion of Skye tossing a log from the fire onto the floor, and ordered everyone out before she called the guards.
Later, a small group of forestals returned to Muria's treehouse, including Greyda, the Speaker of Eleusis. Thriaf again started a fire, but denied doing so. Having gotten better, he opted for a breath of fresh air in the woods, and took Greyda up on the offer of discussing citizenship as they walked. Greyda, Thriaf, and a few others journeyed through the Eastern Ithmia before finally happening upon the young man's former grove on the edge of the Dryad Burial Grounds. He told those gathered that he left Eleusis, both in location and membership, because he did not want to endanger them any more. He knew that fire stalked him wherever he went, robbing him of everything he loved. When he became scared, flames would flow from his fingertips against his will. It confused him greatly.
Despite offers by other forestals to help tame his powers, he insisted that he go to Ulangi to speak with his father about what had happened. Skye was reluctant to do this, as she knew that the shock of finding that he had killed his father would only trigger in young Thriaf another surge of wildfire. However, he urged her to bring him there, and lacking any real argument against it, she acquiesced. She, along with Thriaf and Delphinus, henced to Ratiph's grove, which the young man was shocked to find burnt and blackened. Frightened, he called out for his father. When Skye finally told the man that his father was dead, he refused to believe it until Skye exhumed the remains as solid proof. As suspected, this proved too much for the young Sylvan. He slumped to the floor, limp, as the entire island became engulfed in a raging inferno. So burnt and wounded was his body already that he could not bear the heat of another fire, and so he perished.
At Skye's request, forestals flooded onto the island from Sapience and snuffed out the flames with relative ease. But the victory was on a sombre note for the villagers of Eleusis, for a friend and sometime-inhabitant was dead. Skye delivered a brief elegy as she laid father and son to rest within their grove, and they went to join Thriaf's mother in death, a family once more.