Fan Xiao Xiao is the main antagonist in Derailment , portrayed as a paranoid, controlling businesswoman who becomes tied to the story’s memory- erasure experiment and later escalates into violent criminal behavior. She is played by Liu Zi in the drama’s cast listings.

In the story

  • She is described as Jiang Bo’s adopted mother in one review, with strong control over major business interests.
  • Another synopsis-linked source says she is connected to the Lighthouse experiment and is central to the late-story reveal.
  • Some fan discussion snippets also describe her as stealing experimental equipment and trying to use it to recover data related to her own condition.

Why people mention her

  • Viewers often bring her up because she is introduced relatively late, so her role feels like the “big villain reveal” near the end.
  • She is associated with the deeper sci-fi twist: the story is not just romance, but also about memory manipulation and hidden experimentation.

Cast detail

  • Fan Xiao Xiao — Liu Zi.

If you want, I can also explain Fan Xiao Xiao’s full plot arc in Derailment in simple spoiler-free terms or give the spoiler-heavy version.