Vis à Vis ( episode ) A genome thief switches physical forms with Tom Paris . Summary . Teaser . The Doctor finds Lieutenant jg Tom Paris inside a holoprogram called " Grease Monkey " , which was a 1960s - style car garage complete with " surf rock " music emanating from a nearby portable radio of that era . The Doctor calls Paris ' attention to the fact that his new medical assistant has been rather lax in his duties to improve upon his skills as an assistant , instead choosing to spend the time he should have been spending in sickbay working on a mechanical " patient " of sorts , a vintage 1969 Chevy Camaro . The conversation ends when Paris gets a call from the bridge to take the helm . When he arrives on the bridge he is still wearing his garage overalls . An alien ship emerges out of a spatial distortion just ahead , its outer hull sparking with what appears to be an energy overload . Paris believes that the ship is being powered by a coaxial warp drive , an experimental propulsion system that could be the cause of the spatial distortion . Lieutenant Commander Tuvok ' s readings from the tactical console reveal that the alien ship ' s warp engine s are overloading . Act One . Realizing how dangerous a coaxial warp drive explosion could be to nearby space and with the crew unable to hail its pilot or beam them off the ship , Paris decides to create a symmetric warp field that could possibly contain any instabilities in the alien ship ' s warp core . There is the possibility that the symmetric warp field could cause the to collide with the ship . Captain Kathryn Janeway agrees to Paris ' plan and he carefully maneuvers " Voyager " close to the alien ship so that " Voyager " s warp field surrounds both ships . With the alien ship ' s warp core powering down , " Voyager " receives a hail from the other ship . A humanoid male alien requests repairs to his ship , which Janeway offers help for and which the alien accepts before beaming aboard " Voyager " . The alien identifies himself as , a test pilot from the fourth planet of the Benthan system who is currently test - piloting the very ship that the crew of " Voyager " had put themselves at risk to rescue . As Janeway talks with Steth about helping him repair his ship , Commander Chakotay has a talk with Paris about the lieutenant ' s seemingly lackadaisical attitude toward his duties as both the navigator and the medical assistant before he decides to assign him to helping Steth with the repairs . On board Steth ' s ship , Paris gets to know its pilot a little better with some friendly conversation concerning Steth ' s previous flying missions . Paris tells Steth about the time when he took his father ' s shuttle out for a joyride . At one time during the repairs , when Paris ' back is turned , Steth briefly transforms into an alien female of another species . Steth invites Paris to come with him on his test - piloting adventures , promising that he would have a great time but Paris turns down Steth ' s offer , realizing that he has responsibilities on " Voyager " and that B ' Elanna Torres would be furious if he just took off . Paris then later meets Torres in the mess hall on a lunch date that he is late for , explaining that he was helping Steth with his ship ' s repairs . Torres is wondering what ' s going on with Paris , why he ' s been canceling dates and spending lots of time in the holodeck . Paris tries to tell Torres that nothing ' s going on and that he doesn ' t need to report every moment that he ' s not spending with her to her , causing Torres to storm out of the mess hall . Meanwhile , on Steth ' s ship , he checks with its computer to see how long it will be before his body reverts to its previous form and it reports that it will be three hours and thirteen minutes and that complete genome recovery is imminent . Act Two . The following day , Paris takes Steth into his garage holodeck program to tell him about an idea he had for fixing the alien ship ' s propulsion system that he came up with , similar to a 20th century car ' s carburetor . Sometime during the discussion , when again Paris ' back is turned to Steth , he transforms yet again into the alien female humanoid , though his voice is still that of his male form . He reverts back to his male form again before Paris notices anything . Shortly after , Steth goes into Cargo Bay 2 and uses Paris ' handprint to access all information regarding the lieutenant when Seven of Nine comes into the room and notices what he was doing . Steth says that he was looking for files for polaric modulator s and ends up leaving the room under the pretense of looking for the files elsewhere . Seven warns Steth that he should familiarize himself with the protocols of being on board a Federation ship . The repairs on Steth ' s ship are soon completed and Paris is on board to make a final check on the propulsion system ' s flow field parameters when he notices that one of his tools from his holoprogram ' s toolbox is sitting on that ship ' s computer console . Steth reveals to Paris that he needed that tool to sample his DNA from the cellular residue left on it , finding that Paris ' DNA is compatible , he pins Paris to a wall and grabs him while he and Paris change forms with each other . Now in the form of Paris , Steth stuns Paris ( who is now in the form of Steth ) and sends him and the coaxial warp drive ship on their way while Steth assumes Paris ' life on board " Voyager " . Act Three . Steth , in Paris ' body , begins to assimilate to his life . He has conversations with Chakotay , Kim and The Doctor doing his best to keep up relationships . Chakotay wants him to try implementing some of Steth ' s technology on the ship , starting with a shuttlecraft . He enthusiastically says he can do it , happy to have an immediate task he can succeed in . However , he then has to find sickbay , and has trouble doing it , being caught by Kim in the process and having to explain away his ignorance . Kim reminds him about a golf game they have coming up , so he takes it upon himself to learn the game . When he finally finds sickbay , The Doctor gives him several tasks , but it ' s immediately clear he cannot perform basic functions . After a bit of stumbling , he convinces The Doctor that he has been shirking his duties because he has been trying to live up to The Doctor ' s abilities , an impossible task . The Doctor is convinced he has an inferiority complex and gives him time off to relax . Later , he goes to Torres ' quarters to practice golf and wait for her . She is annoyed he casually continues to go into her personal space after not having an open conversation earlier . Steth quickly adapts and , talking about himself in the third person , makes up a story about how Paris talked to Steth and got some advice , took the day off to see her . She became convinced . Paris , in the form of Steth , wakes up and finds out that he is now on board Steth ' s ship . However , he ' s unable to command the ship to go back to " Voyager " and , furthermore , is soon attacked by various alien ships , accused of being a thief . Act Four . Outside , another alien ship enters and drives off the ones taking Paris into custody . A female humanoid being identical to the form Steth was turning into earlier beam s aboard , and says she is Steth . She says Steth had her body earlier , and Paris then realizes that both he and this female humanoid ( the real Steth ) are victims of a shapeshifting identity thief that was posing as Steth . Meanwhile , Steth in Paris ' body is pushing the fun of his new life and starts to have trouble in the process . He pulls Torres from an important EPS recalibration she was working on with Ensign Vorik to the transporter , attempting to take her on an impromptu picnic on the fourth planet of the Kendren system , where the ship is currently gathering supplies . Torres likes the idea , but quickly turns to her responsibilities . Steth turns on her , holding her head and wondering aloud how he ' s not sure what he ever saw in her . Later , he goes to the mess hall to waste time reading and drinking to intoxication when Seven comes in to remind him he was supposed to meet her in the shuttlebay , to which he doesn ' t give a real excuse . Seven can see he is drunk , and notes he is on duty . Steth tries to get her to join him , but she refuses , saying she ' ll complete the work herself without his help . He goes back to reading , but Seven can see he is reading Janeway ' s personal log s . She confronts him about it , and he threatens her not to interfere with him . She immediately leaves and reports to Janeway . In Janeway ' s ready room , Janeway calls Paris there and confronts him about his behavior . Steth is defensive , and argues away the behavior before offering to go to his quarters for " relaxing . " Janeway orders him to sickbay instead for tests , and this angers Steth . He exclaims there ' s nothing wrong with him and then attacks her , however , she ' s able to call for security . They find the shapeshifter physically assaulting Janeway and shoot him unconscious . They take him to sickbay . Act Five . The alien and Paris decide to work together to bring this shapeshifter to justice , breaking through the lockout commands and getting the warp drive online . They finally are able to get the ship running to find " Voyager " . Meanwhile , The Doctor can ' t wake Paris . Neurological scans didn ' t reveal anything unusual , but a blood analysis reveal traces of a second DNA pattern . When the alien ship returns to " Voyager " , Paris tries to warn the crew about the identity thief . Janeway is initially incredulous and orders a tractor beam to hold the ship until the crew hears from her . However , Janeway , instead of going to sickbay again , goes to the shuttlebay and takes off in a shuttlecraft that has recently been modified with Steth ' s coaxial warp technology . Paris insists to Chakotay that the shapeshifter is now in the form of Janeway and that he can catch the shapeshifter if he releases the tractor beam . He convinces Chakotay he really is himself by mentioning a previous conversation , and Chakotay agrees . While in pursuit of the shuttlecraft , the shapeshifter fires on Steth ' s ship and prepares to go into coaxial warp before Paris decides to hit the shuttlecraft ' s polaric modulator with a chromoelectric pulse to disable its " carburetor " . With the shapeshifter stopped , Paris and Steth bring him back to " Voyager " where Paris , Steth and Janeway are put back in the right bodies and the shapeshifter into the female humanoid form of his previous victim . Steth says that he ' s going to try finding every victim the shapeshifter has violated when he brings it back to Benthos . Later on , Paris brings Torres into his " Grease Monkey " holoprogram to make peace with her for all the hours he felt he should have spent with her , taking her inside the Camaro he was working on to passionately kiss her as the " surf rock " music plays on in the background . Memorable quotes . " " Ow ! Ow ! What do you think you ' re doing , doc ? " " " " An impromptu auditory exam . " " " " Did I pass ? " " " " With flying colors , which leads me to believe you did hear me when I requested you meet me this morning . " " " " Somebody call for a driver ? " " " " How can you be so sure ? " " " " Advanced subspace geometry . It ' s the one course at the Academy where I actually paid attention . " " Links and references . References . Advanced Subspace Geometry ; alcohol ; atrophy ; Avek ; Benthan ; Benthan Guard ; Benthan patrol ship ; Benthan system ; Benthos ; bicycle ; biobed ; blood ; box wrench ; break ; brig ; California ; Camaro ; capillary ; carbon monoxide ; carburetor ; cardiopulmonary reconstruction ; cheek ; Chevy ; chromoelectric pulse ; coaxial warp drive ; Daelen ' s ship ; Delta Quadrant ; DNA stability analysis ; eidetic memory ; Entaban ; exatanium ; Federation ; fridge ; genetic virus ; gesture ; golf ; " Grease Monkey " ; Highway 1 ; holodeck ; holotechnology ; ingrown toenail ; intoxication ; isokinetic containment field ; ; Kendren IV ; Kendren system ; kilometer ; Kotaba Expanse ; Lake Tahoe ; logic ; mechanic ; medical text ; medievalism ; metabolic referent ; ; monument ; neurological scan ; Ninipia Prime ; ; Paris Program Alpha - 1 ; physio - sensor ; plasma manifold ; polaric modulator ; polyduranide ; red alert ; sand wedge ; scan emitter ; selected DNA exchange ; spatial disturbance ; Starfleet Academy ; symmetric warp field ; toolbox ; Trakian ale ; vascular congestion