Jean-Lucien Ferdinand's Links
When Mathis first comes to pretuim Fabula he helps Jean-Lucien feel better about himself and his situation, encouraging him not to close himself up. when Mathis's own returning memories cause a disconnect in his perception of reality Jean-Lucien returns the favor, keeping Mathis on a good path.
Mathis has a very unhealthy dependence on Jean-Lucien for his mental well being. Jean has become the only person he values as much as himself and those feelings do eventually turn romantic for better or worse.