A rangy, long-legged wolf with a dense coat that looks charcoal-gray at a distance and resolves into bands of soot, brown, and silver up close. His winter fur stands in rough ridges along the shoulders, while the shorter hair on his muzzle is weathered and russet-flecked. He waits with his weight tipped forward over his forepaws, as if every pause might become a sprint. Within a minute, most people notice that he keeps nudging a small wooden bead at his throat back to the center of its cord.

Ulo is trusting with Calypso but cautious with everyone else, curious about new scents yet quick to retreat from unfamiliar hands. He can be playful when safe, nosing at loose objects and inviting pursuit, but turns intensely watchful when Calypso is distressed. When she is confident, he ranges ahead; when she is troubled, he refuses to leave her side.

Ulo was Calypso's wolf companion long before the fall that separated them. On the day she fell, he was away tracking a wounded animal and returned to find only the signs of catastrophe and the absence of the person whose trail he knew best. He searched until exhaustion, then survived by ranging between settlements and avoiding people who saw a starving wolf as a threat. When Calypso accepted Bersuka Varkoi's mythic calling, the promise woven into that power drew Ulo back from wherever his search had taken him. He appeared at dawn, gaunt but unmistakably himself, and went straight to Calypso. He is still learning the altered scent of her and the strange tug of the force that returned him. He remembers the long absence as a trail that simply stopped, and remains wary of being left behind again.