Similitude ( episode ) During an engine performance test , Trip Tucker is critically injured and left comatose in sickbay . Phlox suggests that Tucker ' s only hope for survival is the creation of a " mimetic simbiot " – in other words , a clone . The crew and Trip ' s clone have to face the unforeseen emotional ramifications of his creation . Summary . Teaser . At a funeral ceremony , the entire crew gathers as Captain Jonathan Archer is eulogizing a dead crewman – Commander Charles Tucker III . Act One . Two weeks earlier , the is continuing to explore the Delphic Expanse , and testing upgrades to their warp drive in order to do it more quickly . T ' Pol and Tucker have another Vulcan neuro - pressure session and discuss it . This time , Tucker tries it out on T ' Pol ' s foot , mostly successfully . The next day , they start the test . First , they get to warp 4 . 9 like normal , then Tucker starts to compress the antimatter stream in the warp core . It appears to work initially , but , unfortunately , only seconds later , a primary injector flare forces Tucker to do a manual shutdown . While on the top of the warp core , he is injured by a nearby explosion and falls . Helm control is lost and the " Enterprise " is thrown out of warp into a polaric field of some type . Emergency team s are dispatched to tend to multiple injuries , including Tucker ' s . Archer learns later that nucleonic particle s flooded the plasma manifold s , causing the injector flare . Tucker ' s action saved the ship from a breach . It will be weeks before they can get the ship back to normal . T ' Pol is in charge of repairs , and later has EV teams retrieve a sample of the particles from the field . The highly magnetic properties of the particles don ' t appear to be a problem now , but are building on the ship ' s hull and could become a problem if they are not able to clear the field in time . Archer tells T ' Pol to do whatever it takes . Unfortunately , Doctor Phlox must inform Captain Archer that Tucker has slipped into a coma due to extensive neural damage . He has an unconventional proposal to use a Lyssarian Desert Larvae he happens to have to make a clone of Commander Tucker ( which will grow to maturity very rapidly , and have a lifespan of only about fifteen days ) and harvest neural tissues from it . Because of highly sensitive ethical implications , Archer does not make a decision right away . Soon , however , Archer agrees to allow the cloning procedure , sacrificing the ethical implications for the sake of the mission ' s objective , and perhaps the life of his friend . Phlox informs Archer the procedure was a success , and Archer sees the new infant . Act Two . Phlox , pleased at holding a newborn after a long time , informs Archer and T ' Pol the infant is healthy , though needs a name . He calls him Sim . The clone quickly grows from an infant to a child . Sim can read soon , though interestingly , the boy demonstrates that he has the memories of Tucker at the same age , including his family , by saying he already knows what the book is about . Sim is as curious about the world as Tucker is , both about technology and about his existence . Archer decides to be the one to tell him the truth , and takes him to his quarters and they have small talk , with Sim pointing out Zefram Cochrane on the wall . They then the launch bay to fly a remote - controlled model , and the real questions start . Archer takes Sim to sickbay , where Tucker ' s body is . Sim recognizes Tucker and gets it all on his own . Archer does say Sim ' s more than just a copy , since he ' s making his own memories . He also says Tucker needs something from him , and that the operation is painless . Sim believes them and wants to go fix the model , seemingly taking it all very well . As Sim ages , he starts to help with the repairs . He ' s happy to do it , though disappointed when he thinks T ' Pol doesn ' t want to hang out with him because he ' s different . T ' Pol insists they need to be focused on the repairs . She ' s called away by Archer to find that , unfortunately , because the particles building on the hull have a dampening field effect , at the rate the crew has been proceeding , every system on the ship will fail before the repairs are complete . Act Three . Sim soon comes up with a solution to the ship ' s problem , and , while trying some key lime pie , he runs it by Malcolm Reed in the mess hall . Reed confirms they could re - direct the phase cannon s to fire at the launch bay so they can launch the s . Sim also runs the idea by T ' Pol later that night and , although risky , she agrees it appears to be the only viable option . It involves a fusion overburn , which has never been attempted by a shuttlepod . Sim turns the conversation to her and Tucker ' s relationship , confesses his feelings for her , and wondering if they ' re his or Tucker ' s . Later , Sim goes to Archer and insists he pilot one of the pods since it is his plan , but the Captain assigns Reed and Travis Mayweather instead . Sim challenges his decision on the basis that he ' s only concerned about Tucker , but Archer points out ( again ) that they need Tucker to survive . The plan begins . Sim and T ' Pol set the targeting scanner s of the cannons and fire , successfully freeing the launch bay . Reed and Mayweather fly out and fire their respective grappling arms . Sim orders their thrust power and they try to pull the " Enterprise " , but it ' s not moving . They push their engines a little harder and , just as Archer decides to abort , the ship starts moving . The plan is a success , as their inertia will keep them going and they ' ll be out in six hour s . Later , Phlox informs the captain of a startling discovery . According to his new predictions , and contrary to his earlier determination , Sim won ' t survive the transplant because Human DNA is not as resilient . Archer ' s decision just got a lot more difficult . Act Four . Sim is devastated to hear this news , though he does say he only has a few days left , anyway . Archer doesn ' t see it that way , but then Sim states another complication : experiments by the Velandran Circle which attempted to prolong the lifespan of mimetic simbiot s . Phlox didn ' t mention it because the evidence was very little . Despite that , Sim declares that there ' s a chance he can live a normal life . The next day , Archer finds Sim in Tucker ' s quarters , obviously dwelling in Tucker ' s life . He begins to question why his life is not seen as as valuable as Trip ' s . He confronts Archer about the situation , saying he didn ' t control what happened to Trip , and he , in a way , could be saving him by taking on his life . Archer is insistent that Sim is " not " Trip , and that he will stop at nothing to complete the mission , which requires Trip . He appeals to the fact that Sim has Tucker ' s memories , so he knows Archer ' s resolve . Sim doesn ' t think Archer will murder , but Archer tells him not to make him a murderer . Sim later has agreed to the procedure , and goes to engineering to help out T ' Pol beforehand . She wonders why he wants to spend his last hours of life like that , but gives him something to do . Later , Reed finds out on the bridge that launch bay controls have been tampered with . Archer goes down there to find Sim having planned but then aborted an escape attempt . Sim says that what stopped him was the thought of his sister , insisting on the fact that she was his sister as well as Trip ' s , and that he doesn ' t want what happened to her to happen to anyone else . He leaves to go back to his quarters to wait . Just before the surgery , T ' Pol comes to Sim ' s quarters to say her goodbyes , giving him a kiss , something she had never done with Tucker . Sim returned the gesture , showing that he meant something to her , more than just being a clone to save Trip ' s life . Sim goes to Sick Bay , where Phlox and Archer are waiting . Sim tells Phlox he doesn ' t just remember Trip ' s childhood , he remembers his own , and Phlox was a " damn good father . " Phlox says Sim was a damn good son . Sim then tells Archer that just as Archer was meant to be a starship captain , he realizes saving Trip ' s life is what he was meant to do . In his final preparations , he stands near the comatose Trip and says , " You owe me one . " Back in the present , at the funeral ceremony , the crew , including a recovered Trip , pay their last respects to Sim as he is placed in a torpedo tube and fired out into space . Memorable quotes . " " The most difficult test facing any captain , any crew , is the loss of a shipmate . We ' ve come here to honor one of our own . In the time we knew him , he showed us just how much one life can truly matter . We will never forget what he did for us , and for the ship he loved so much . We will go forward with renewed determination to complete this mission , so that his sacrifice won ' t just have been for the people on this ship , but for all the citizens of Earth . " " " " Regarding the Lyssarian procedure Doctor Phlox proposed , may I ask if you ' ve reached a decision ? " " " " I approved it . " " " " Are you aware that the Lyssarian Prime Conclave has banned the creation of simbiots ? " " " " We don ' t answer to the Lyssarian Prime Conclave . " " " " Simbiots are living , conscious entities . We ' ll be growing a sentient being for the sole purpose of harvesting tissue . " " " " I ' m aware of the ethical implications . If we weren ' t in the Expanse , maybe my decision would be different . But . . . we ' ve got to complete this mission . Earth needs " Enterprise " . " Enterprise " needs Trip . It ' s as simple as that . " " " " Can he do any tricks ? " " " " I haven ' t taught him any . Mostly what he does is eat , sleep , and , uh , not fetch . " " " " I ' m not talking about an adolescent crush . That was . . . well , that was two days ago . " " " " I have his memories . I have his feelings . I have his body . How am I not Trip ? " " " " I must complete this mission ! And to do that I need Trip ! Trip ! I ' ll take whatever steps necessary to save him . " " " " Even if it means killing me ? " " " " Even if it means killing you . " " " " I was all ready to do it . " " " " What stopped you ? " " " " Where the hell was I going to go ? We ' re nowhere near any habitable planet . Didn ' t really want to spend the rest of my life floating around in a shuttlepod , which doesn ' t even have any toilet facilities . Can you imagine a lousier way to spend your old age – cooped up in that thing , peeing in a bottle ? Actually , I can imagine a worse fate . " " " " What would that be ? " " " " Being stuck in there with Malcolm ! " " " " It ' s not that I ' m scared of dying . It ' s just that . . . I can ' t imagine not being here tomorrow . " " " " Do me a favor when this is over . If Commander Tucker decides to do any more modifications to the engines . . . tell him to watch his ass ! " " " " I ' m sorry I doubted you , Doc . " " " " No need to apologize . " " " " Yes , there is . You see , I don ' t just remember Trip ' s childhood . I remember mine . You made a damned good father . " " " " You were a damned good son . " " " " You said to me once that commanding a starship was what you were meant to do . I guess this is what I was meant to do . Good luck , Captain . " " " " You owe me one ! " " Links and references . References . " A Night at the Opera " ; antimatter injector ; ; architecture ; armadillo ; Bedford ; birthmark ; bruise ; cannula ; cerebrum ; ; coma ; clone ; cut ; Delphic Expanse ; Dennis ; Denobulan ; diagnostic ; diamagnetic field ; diaper ; DNA ; dollhouse ; Earth ; empirical evidence ; engineer ; Enriquez ; epidermal layer ; ethical implications ; EV team ; feces ; ferric ion ; fertilizer ; field coil ; funeral ; fusion overburn ; garden snake ; genetic memory ; genetic sequencing ; glue ; horse ; injector flare ; injector port ; key lime pie ; kilodyne ; kilometer per hour ; Lyssarian ; Lyssarian Desert Larvae ; Lyssarian Prime Conclave ; magnetism ; Martian ; Marx Brothers ; Massaro ; medical tricorder ; mimetic simbiot ; name ; neural node s ; neural tissue ; nucleonic particle ; Orsic fern ; phase cannon ; plasma assembly ; plasma rifle ; playing card s ; REM cycle ; salve ; ' ; " Shuttlepod 2 " ; Steven ; system tap ; targeting scanner s ; toilet facility ; teething stage ; ; ; urination ; Velandran Circle ; viral suppressant ; Vulcan ; Vulcan neuro - pressure ; ' ; warp drive ; Xindi weapon ; Zefram Cochrane ' s statue Deleted references . ocean skimmer ; statistics ; suspensor coil