A Chelgrian military officer carrying a grief so profound it has hollowed him out. Sent to the Culture Orbital Masaq' on an ostensibly diplomatic mission, he carries with him a purpose known only to the leaders of his civilisation.

A Chelgrian composer of extraordinary talent, living in self-imposed exile on Masaq' Orbital. He fled Chelgrian society in disgust at its caste system and has no desire to return or to engage with his homeland's politics.

A Culture Contact drone of antique appearance, with a meter-tall casing of delicate pink porcelain held in a lattice of glowing blue lumenstone. Tersono is fond of old things and antiquarian style. It organises Quilan's visit to Masaq' Orbital, hosts recitals aboard the ceremonial barge Soliton, and persistently tries to engineer a meeting between Ziller and Quilan.

Admiral-General Sholan Hadesh Huyler, a personality construct of a long-dead Chelgrian military officer revived from a substrate rescued from the wreck of the Winter Storm. He is implanted inside Quilan's modified Soulkeeper as a co-pilot for the mission, providing commentary, cultural expertise and serving as a failsafe. He is secretly a Culture agent turned by Special Circumstances while still in storage on Aorme.

A Homomdan – a massive, gentle, three-legged alien – living on Masaq' Orbital. An affable observer of Culture life, Kabe provides a warm outsider's perspective on the society he has chosen to inhabit.

The AI Mind that runs the Culture Orbital Masaq'. Ancient, thoughtful, and burdened by its own role in the long-ago war that set current events in motion. A gracious host with eight hundred years of guilt.

A Culture scholar of simian-adapted human form who has spent thirteen years studying the dirigible behemothaur Yoleus inside the Oskendari airsphere. He discovers the dying behemothaur Sansemin, encounters a mortally wounded Culture agent with a warning about the plot against Masaq' Orbital, and attempts to carry the message out. He is killed by Eweirl but restored a galactic cycle later from a backup hidden in his aunt's necklace.

Estodien Visquile, a high-ranking Chelgrian religious figure who goes between the mortal world and the Sublimed. He is the mastermind behind the plot to destroy Masaq' Hub, recruiting and training Quilan for the suicide mission. He is killed by a Culture EDust terror weapon on the seastacks at Youmier in retribution.

Major Worosei, Quilan's wife and fellow Army officer. She narrates the prologue, where she is forced to leave Quilan trapped beneath a land destroyer during the Caste War. She dies instantly when the privateer Winter Storm is destroyed by Invisible forces, her Soulkeeper unable to save her personality. Her loss is the central emotional wound driving Quilan throughout the novel.

A fifth-order Decider in the dirigible behemothaur Yoleus' 11th Foliage Gleaner Troupe, given the title Interpreter when assigned to Uagen Zlepe. A small, winged creature who serves as Uagen's guide and translator within the airsphere, she is badly burned shielding him during their escape from the dying Sansemin.

An elderly human woman who serves as a representative of Masaq' Orbital's General Board. She has long white hair, deeply lined features, and a warm presence. She accompanies the welcoming party for Quilan and offers a sincere apology for the Culture's role in the Caste War.

A large, white-furred Chelgrian male who serves as Visquile's enforcer and operative. He kills the Culture agent inside the airsphere's behemothaur Sansemin and murders Uagen Zlepe to prevent the warning from reaching the Culture. He is killed by the EDust terror weapon on the seastacks at Youmier.

The oldest monk at the monastery of Cadracet and Quilan's mentor and counsellor. A frail, elderly Chelgrian who survived the Caste War by hiding in a grain-store drum. He guides Quilan through his grief and arranges the visit from Colonel Ghejaline.