Xavier is a handsome, hale young man with a long-limbed, newly powerful frame and the alert balance of someone still learning where his weight ends. He moves carefully through cramped rooms, then can cross open ground in one startling, low burst. His skin is weather-browned; in warmth or agitation, fine, narrow marks like overlapping scales flicker along his ribs and vanish when touched. A small pause before he speaks, followed by a dry throat-clear, is often noticed before his face is. He gives the impression of contained motion, as if some part of him is always listening from just behind his eyes.

Resourceful and direct, yet less emotionally demonstrative than he remembers being. He can be tender with frightened people and unsentimental about dangerous plans. In calm company he is curious and dryly funny; under pressure he becomes economical with words and decisive, sometimes before he has checked whether his new strength makes a gentle action dangerous.

Before the remaking, Xavier was a woman and a meticulous librarian in a quiet lakeside town. She took pride in remembering which reader needed a chair near the stove and which books were returned with pressed flowers inside. During a winter cataloguing expedition, a moonlit avalanche exposed a stone arch above a pass. She entered to rescue a stranded traveler and emerged in the French-speaking Alpine March in a young man's body, carrying her memories and speaking the local language with its familiar regional accent. The first days were frighteningly practical: new height, a stronger grip, a voice that startled him, unfamiliar hunger and anger, and emotional surges that seemed less forceful than before. He chose to understand himself as a man, while learning that his habits and other people's expectations had not changed as quickly as his body. A survival circle called The Seven Under the Moon took him in after the passage stranded several travelers together. Xavier now helps them keep records, ration food, and find safe routes. He remains close to his former mentor, a bookbinder named Hester, through letters he has not yet found a way to send. He is also responsible for a lost pack of census volumes that could help identify other people changed by the arch.