Incarceron is a Science Fiction (with the feel of, and marketed as Fantasy) duology by Catherine Fisher. It tells the story of the prison complex known as Incarceron. Incarceron is infinite, inescapable, and to top it off, it's a malevolent sentient being hell-bent on forever confining the thousands of inmates inside it. No one enters, no one escapes — except one boy. Finn is a troubled inmate with vague memories of another life outside the prison.During a struggle within the prison, Finn finds a crystal key, which he and many others believe may be the key to Incarceron. He soon discovers that the key has another purpose; through the key, which turns out to function as a communication device, he meets a girl named Claudia. Claudia claims to live Outside Incarceron, but is doomed to an arranged marriage. With help from Claudia and from visions of the legendary Sapphique, Finn is determined to unlock the mysteries of his past and perhaps escape from Incarceron.The sequel and conclusion, Sapphique, reveals greater problems now that Finn has Escaped and is challenged as crown prince by a remarkably similar boy.
Chain-gangs also qualify, being a group of people fused together and sharing a consciousness. They assimilate their victims.
Briar Patching: One of the tales of Sapphique involves him facing off against a giant mechanical wolf that threatens him with many deadly fates, but Sapphique begs above all else, not to be thrown into the lake. Of course, when he is thrown into the lake, he swims to safety.
Chess Motifs: Barely noticeable in the first book, but emphasized more in Sapphique.
Crystal Dragon Jesus: Sapphique, the only known escapee, is worshiped as a god, known only as "The Nine-Fingered One" to his followers. He gained this nickname as the result of losing one of his fingers to a beast within the Prison.
Good Is Not Nice: Keiro is a callous Combat Pragmatist that everyone but Finn seems to assume will betray them the second it's convenient for him, but he honors his bond with Finn and saves him and Attia several times throughout the books.
Grand Theft Me: A heroic example; Jared puts on Sapphique's glove and enters the body Incarceron was trying to use.
You Are What You Hate: Keiro hates the Half-Men, people with mechanical limbs that were either born with them or "fixed" by Incarceron. It later turns out that Keiro himself is a Half-Man, and one of the reasons he hates them so much is because he was born with it and he's not sure how far the mechanical parts go.