Sim Sim was a mimetic simbiot of Commander Charles Tucker III , created by Doctor Phlox using a Lyssarian Desert Larvae . He was created after Tucker was injured and rendered coma tose due to an encounter with a spatial anomaly in 2153 . Sim ' s purpose was to provide Phlox with vital brain tissue , which was to be used to treat Tucker ' s condition . Sim resided aboard , where he lived a lifetime in fifteen days . History . Development . Sim ' s development from a Lyssarian Desert Larvae began with cellular division in a growth tank inside , following insertion of DNA from Tucker . Two days later , Sim had developed into a fetus , which was sensitive to light . He had been transferred to a birthing tank , which was usually covered by a sheet , and the lighting in " Enterprise " s sickbay was deliberately dimmed . Inside the tank , the fetal Sim was surrounded by a nutrient solution . Phlox expected Sim to be " born " the following day , and believed that once he aged to the approximate age of the real Charles Tucker , the clone could be a donor of the needed tissue and still live out the rest of his short lifespan . Becoming Tucker . After his " birth " , Phlox became a surrogate father to him . He named him " Sim " and cared for him as Sim grew quickly to a boy , a teenager and an adult over just a few days . To the surprise ( and vague unease ) of the crew , as he grew older , Sim ' inherited ' all of Trip ' s memories from that age . Archer informed him of his true existence and purpose and Sim accepted it . As the days went by , Sim became part of the crew , putting Tucker ' s remembered engineering skills to good use . He even saved from a polaric field . Sim had strong romantic feelings for T ' Pol , but she seemed somewhat discomforted by his advances . Meanwhile , Phlox discovered through further testing that he was incorrect ; Sim would not survive the tissue transplant . Wanting to live . Sim discovered that an experimental enzyme might extend his life beyond the fifteen days to the length of a normal human lifespan . Phlox told him that there was no proof that the enzyme would work and that it would take too long to determine if it would work - thus aging Sim beyond the point where he could donate the necessary tissues to Tucker - and that if it did work , then Tucker would die . Sim thought about stealing a to escape , and went as far as setting up the computer to aid in this escape , but he realized that if he did this , then Tucker would die and the " Enterprise " s mission to stop the Xindi might fail , causing the annihilation of mankind - not to mention that Sim would have to live the rest of his incredibly short life alone in space , " peeing in bottles " because the shuttlepod was not equipped with restroom facilities . With this in mind , he decided to submit to the operation . T ' Pol kissed him goodbye and he reported to sickbay . The ultimate sacrifice . Sim was painlessly killed by the operation , and was given a full - honors burial in space by the crew , including the resuscitated Tucker . Archer conducted a funeral service for Sim , noting that the entire crew was grateful for the contributions he made in his short lifetime . Sim was " buried " in a torpedo capsule with the serial number 2744586 . ( ) Personal relationships . Phlox . Dr . Phlox was the man who created and raised Sim during his first few days . Right before the transplant , Sim told Phlox that even with all of Trip ' s memories , including those memories of Tucker ' s parents , he considered Phlox to be " a damn good father . " Phlox told him he had been " a damn good son . " T ' Pol . Sim , like Trip , was attracted to T ' Pol , but unlike Trip , didn ' t have the time to waste . He confessed his feelings to her , along with the ambiguity of their origins , to which she couldn ' t answer either way . Right before he went to sickbay for the final time , T ' Pol said the crew , and she , would miss him , and then kissed him goodbye . Sim felt he " couldn ' t have asked for a better going - away present . " Legacy . Because Sim revealed his feelings for T ' Pol to her , she knew , logically , that Tucker felt the same way . This led to a romantic liaison between T ' Pol and Tucker months after Sim ' s passing . ( ) Over a year later , T ' Pol and Tucker ' s DNA was used to create the first ever Human - Vulcan hybrid . ( ) Background information . In most scenes , Sim ( as an adult ) was portrayed by actor Connor Trinneer , since he usually played Charles Tucker . Child versions of Sim were played by Maximillian Kesmodel ( apparent age 4 ) , Adam Taylor Gordon ( apparent age 8 ) , and Shane Sweet ( apparent age 17 ) . An unknown performer appeared as Sim while he is depicted as a baby ( both as a newborn and seemingly as an eight - month - old ) . In the final draft script of " Similitude " , Sim was commonly referred to ( apart from in dialogue ) as " Sim - Trip " . In the same script , however , the character was twice referred to as Tucker . The first occasion was in the teaser , hiding Sim ' s true identity , and the second instance was apparently as a misprint that gave his name as " Trip " ( rather than " Sim - Trip " ) , in reference to Sim giving Archer a smile in the launch bay prior to Sim ' s operation . The " Similitude " final draft script also specified , " " Sim - Trip has a light Southern accent . " " Concerning Sim when he is seemingly a seventeen - year - old , the script remarked , " " He ' s clearly developed an odd self - awareness about his own , bizarre situation . " " To describe the adult , a note in the script commented , " " From this point forward , Sim - Trip will be played by Connor Trinneer . " " None of the other actors who played Sim were referred to by name in the script .