My Contracted Ancestor Is a Bit Cheating

She was the most unexpected piece in his thousand-year chess game. He was the single most dangerous variable in her life. A soul symbiosis contract forcibly binds the lonely people in the two worlds. He gave her strength and lies, and she gave him calculation and sincerity. They thought they were playing a game, but they didn't know that they were already part of a bigger game within a game. When the memories that have been sealed for thousands of years are revealed, the writer of history reveals his true face—— Should they continue to be chess pieces of fate, or join forces and become the new chess players of this game?