This is a slow. lyrical, and imaginative book. Cobalt is an android, born in a vat, implanted with a false childhood, and destined to be property for all of his existence. He's currently owned by a space-station hotel owner, who uses him for bartending, as a concierge, and sometimes rents him out for other services on request. One night, while tending bar, he meets a young man on his way to the stars.
Liyan is brilliant and hard-working, and has managed to work himself through the education and testing needed to gain a job on the crew of a space liner. He's about to take his first trip off this station where he was born, and explore the wonders of a wider universe. In a moment of exalted delight, as he takes a drink and has a moment's conversation with the blue-haired bartender, he's aware of a connection. As they chat, he realizes that the freedom he's about to embark on is one that Cobalt can never have.
And so he promises to write, via communication waves, from the places he visits. He can't give Cobalt - a very expensive property - his freedom. But he can let the android see by proxy a dozen worlds he will otherwise never experience. And Cobalt serves as Liyan's sounding block, his anchor, his secret friend, and an uncritical ear in which Liyan can expound on his new life.
The letters Liyan writes are lovely, the worlds fascinating, and the low-key emotions poignant. This is a very slow burn book, and by the end I grew just a little impatient with the travelogue parts of the letters, as lovely as they were. But the slow build reaches a satisfying ending, (although I was left wondering if the MCs would do anything to tackle the bigger societal issue and not just the personal.) Recommended for those who love a slow burn full of imagination.