At some point during his time on Starchaser, Fen believed himself kidnapped by the insane Dr. Xina Sev (who we later learned was his nickname for Inada), who was doing experiments on Romulan and Vulcan telepathy. Somewhere during this time, Fen breaks out with a Romulan female named Aryienand returns to Starchaser, he starts having hallucinations which are really visions of Fallen/Aryien's activities.
The time period when this happened is totally accounted for, as ships logs state he spent much of his time freaking Cam out by talking to her from Jeffrey's Tubes and trying to convince her there were creatures in the walls conspiring to poke her eyeball plant.
It is yet unknown what brought this personality into Fen's mind, but he became increasingly violent after playing her out. The Girl, Aryien is confirmed deceased though her cause of death is unknown. Fen Described her as an indestructable Telepathic Assassin, though others reported she was simply a food beggar.