The Obsidian Man — Jon Wilson

All his life, Holt has dreamed of leaving his life of drudgery to join the legendary Danann, a mysterious race of rangers and magicians. When trolls threaten his village, he sees his chance in the arrival of Kawika, a handsome ranger sent for protection. But things take a deadly turn when a demon appears, leading an army of horrible creatures. The village goes up in flames, Kawika vanishes, and Holt finds himself wandering lost and alone in the wilderness.

Rescued by the Danann, Holt suffers both physical and psychic scars. However, Kawika's lover, Keone, hopes to use that connection to track and destroy the demon responsible for the attack.

Unfortunately, the link works both ways -- Keone can track through it, and the demon can use it to invade Holt's mind. As the pursuit continues, Holt's sanity begins to slip away. Gradually the realization dawns that instead of helping Keone defeat the demon, he may be leading them both into the demon's deadly trap.