: Mulder's theory is bolstered by subtle changes: the previously right-handed Willis begins using his left hand (Dupre's dominant hand), forgets Scully’s birthday (which he normally shares), and develops a sudden tattoo that mimics Dupre's.
: At the hospital, Willis flatlines for several minutes while Dupre is simultaneously declared dead. Just as Dupre's life ends, Willis is miraculously revived, leading Mulder to suspect that Dupre's consciousness has possessed Willis's body.
The story of The X-Files Season 1, Episode 15, titled centers on a supernatural soul-swap between an FBI agent and a violent criminal during a botched bank robbery. Plot Summary