Skippius is a broad-shelled male tortle with weathered olive-green scales, a dark amber shell patterned like overlapping brass plates, and calm black eyes that seem perpetually engaged in careful measurement. He keeps his shell meticulously clean except for one narrow band near the lower right edge, which is permanently darkened by oil and soot from years of resting tools there. A copper monocle-like measuring lens hangs from a cord around his neck, though he often forgets to use it. He wears a reinforced artificer's coat tailored around his shell, a shield strapped to his forearm, and a belt crowded with labeled vials, wire, chisels, and tiny clockwork components.

Skippius is patient, dutiful, and intensely curious. He speaks with the confidence of someone who remembers every technical detail but none of the people who taught him. He does not feel troubled by his amnesia and considers his missing past irrelevant unless it contains information necessary to prevent future harm. He is gentle with frightened creatures, exacting with machinery, and baffled by anyone who values tradition over evidence.

Skippius awoke alone in a sealed stone workshop beneath a collapsed observatory. He had no name, no history, and no memory of how he came to be there. Around him were dozens of broken inventions, shelves of carefully catalogued components, and a half-finished brass automaton shaped like a small canine. The workshop's walls were covered in diagrams written in his own precise hand, but every personal reference had been scraped away. He chose the name Skippius after finding it stamped on the inside of his copper measuring lens, though he has no idea whether it was his name, his maker's name, or the name of a particularly stubborn screw. He spent years in isolation repairing the workshop, studying the diagrams, and teaching himself to finish the brass automaton. The result became Cavil, his Steel Defender, whose movements sometimes seem to anticipate Skippius's thoughts. During that solitude, Skippius developed an almost religious devotion to order, repair, and the protection of innocent life. He does not mourn his lost memories because he cannot feel attachment to people or events he cannot recall. Instead, he regards amnesia as a practical condition, like a cracked gear or an empty fuel cell. If his past matters, he reasons, it will eventually present evidence. Until then, he will build a better future, one carefully tested invention at a time.