Gwenna has a pretty, almost doll-like face that becomes startling when she grins: her broad mouth shows two long, pointed canines, and her inward-tilting yellow eyes hold steady even when the rest of her face is animated. Tired shadows sit beneath her thin, slit-like pupils. She is fair-skinned and blushes readily, especially when praised or excited. Her dirty-blonde hair is divided into two unruly buns, with a straight fringe and chin-length side locks; loose strands spring free whenever she moves. She waits with her weight pitched forward onto the balls of her feet, knees softly bent, as if standing still is merely the pause before a leap. When she eats, she turns food with her tongue before biting, a small feline mannerism that people notice only after they have noticed her teeth. She moves in sudden, neat bursts, landing almost soundlessly, and leaves behind the impression of a cheerful child who has learned exactly where to put a knife.

Gwenna is exuberant and quick to praise, yet has a clinical streak that turns people into puzzles when she is excited. She can be sincerely tender with the frightened and injured, but her affection becomes possessive when she decides someone is special. In a safe camp she is playful and helpful; under pressure she grows methodical and startlingly calm. When she feels dismissed, her mood can flip from bright teasing to wounded intensity, though she does not become quiet or deferential.

Gwenna grew up in a roadside hospice where her mother, Sella, treated caravaners and her father repaired harnesses. She learned to clean instruments, remember faces, and make frightened patients laugh. At sixteen, a wounded mercenary arrived babbling about a buried Titan relic. During the fever that followed, Gwenna held his hand while he died; she later found a strange, dark-gold sediment in a smear of his blood. She became convinced that blood could preserve a person's history, and that careful attention to someone was a form of devotion. She left home after her mother discovered her secretly keeping labeled vials from patients.