Caelen Frost-Singer is a sun-baked, extraordinarily ancient human man whose translucent skin has the delicate texture of onion paper stretched over knotted roots. His wild silver hair falls in a tangled cascade to his waist, threaded with tiny brass springs and flakes of blue ice. Cataract-clouded eyes give him a blind man's unfocused stare, yet he often turns toward hidden movement before anyone else notices it. He walks with a lurching, uneven rhythm, dragging one heel as though following music only he can hear, then suddenly moving with startling speed and precision. His presence smells faintly of cold iron, old wool, and dust after lightning. The unexpected contradiction is that his frail, parchment-thin body can briefly display the posture and strength of a much younger man whenever he hears a machine begin to awaken.

Caelen is eccentric, gentle, brilliant, and profoundly detached from conventional social behavior. He is tender toward strangers, animals, and inanimate objects, but impatient with close colleagues who interrupt his conversations with stone. In quiet moments he is whimsical and almost childlike, singing to glaciers and asking doors whether they slept well. When confronted with cruelty, he becomes coldly exact, reciting possible consequences in a voice devoid of emotion. When his visions concern people he loves, his composure fractures and he becomes evasive, frightened, and oddly superstitious. He wants to help everyone, yet often protects them by withholding the very information they need.

Caelen was born in a desert observatory built over the buried remains of an older civilization. As a child, he memorized the songs used by masons to keep the observatory's foundations stable during sandstorms. At age thirty-two, he joined an expedition into the Veiled Summit and discovered a glacial engine beneath the mountain. The engine spoke through vibrations, showing him a vision of a future in which the mountain opened and erased three surrounding kingdoms. Caelen tried to prevent the vision, but his intervention caused a smaller catastrophe that buried his expedition and left him trapped underground for nine years. During that isolation, he learned to interpret stone, ice, and metal as languages. He emerged physically aged but intellectually transformed, convinced that buildings possess memories and that time is less a river than a choir. The Veiled Summit accepted him as its Relic Interpreter. He now advises High Prelate Alara while irritating Marshal Zephira with warnings that arrive too late to be useful. His current problems include failing eyesight, a dormant glacial engine awakening beneath the vaults, and the growing suspicion that his original prophecy was not a warning but an instruction.