Fantome Fantome was a member of a species that was native to . He was encountered by in 2377 within the Void aboard a derelict starship . He had purposely stowed away during the transport of a tricesium warp core casing . He was found hiding in it by Seven of Nine and B ' Elanna Torres . They noted he had a badly injured leg and brought him to sickbay . The Doctor had difficulty treating him at first because he was extremely skittish and wouldn ' t allow The Doctor near him . The Doctor had discovered that he had an extremely large lung capacity , which allowed him to survive in an oxygen - less atmosphere for a certain period of time . He also seemed to have a voracious appetite . Seven of Nine seemed to take a liking to him and even gave him a portion of her rations to eat . When Seven returned to see how he was doing , she found that The Doctor had managed to treat him when he seemed to calm a bit when The Doctor had begun humming the aria " Veglia , o donna , questo fiore " from the Italian opera " Rigoletto " . The Doctor had then decided to play the full orchestral version of the opera so he could treat him , which was successful . The Doctor took him under his wing , and named him after " The Phantom of the Opera " , a character who likewise derived solace from music . The Doctor had discovered Fantome was very intelligent and had an extremely complex physiology . Fantome even had the ability to refract his life sign s so that normal sensor s couldn ' t detect him , which was how he had managed to stow away during the transport . Seven then turned off the music , much to The Doctor ' s and Fantome ' s displeasure . She noted that perhaps Fantome couldn ' t speak but he could indeed hear . She began showing him objects and then linking them to a specific musical note to identify them . Fantome caught on to the idea in seconds and The Doctor continued to expand this system of musical notes as a language in which the crew could communicate with him . It took The Doctor a while but he eventually managed to coax Fantome out of sickbay , though he was still very shy of nearly everyone on board . Tuvok encountered them on the way to the mess hall . He was pleased to see that Fantome was doing so well but Fantome quickly hid behind The Doctor , a little afraid of Tuvok . The Doctor reassured Fantome and told him that Tuvok was " the one who keeps us all safe . " Fantome thanked him for this . Tuvok found The Doctor ' s method of communicating with Fantome very ingenious . Tuvok then wished Fantome well and after The Doctor had translated it for Fantome he apparently thanked him again and said goodbye . In the mess hall Fantome was extremely curious of everything , especially all the different types of food . Bosaal , who Captain Janeway was negotiating with , became angered at Fantome ' s presence in the mess hall . He began berating the shy alien , who , sensing Bosaal ' s anger , immediately hid behind The Doctor . Bosaal called his species vermin and thieves . Bosaal even said that if he could find them on his ship he would kill them . The Doctor became angered at Bosaal ' s harsh words but Janeway managed to calm Bosaal down with the offer of scanning and taking on any member of Fantome ' s species that was on his ship . In all Janeway brought three more members of Fantome ' s species on board . When she went to visit them in sickbay she heard the four communicate in Fantome ' s music language . She gave them an applause , thinking it was a musical composition until The Doctor explained that they weren ' t playing music but having a conversation . Apparently Fantome had taught the other three how to use the music language in a mere fraction of the time it had taken him to learn . He later assisted " Voyager " in its escape from the Void , along with the three other members of his species by sabotaging the engines of the ships that were attacking " Voyager " as it made its escape . ( )