Ishara Yar Ishara Yar was a female Human in the 24th century . She was the sister of Natasha Yar . She grew up on Turkana IV where she was active in the Coalition . Yar was born on Turkana IV in 2342 . Ishara ' s parent s were killed just after she was born , after which she and her elder sister , Natasha , were looked after by " " some people " " for a few months who later abandoned them , leaving Tasha to care for them both . In 2352 , when she was old enough , Ishara allied herself with the Coalition and was subsequently implanted with a proximity detector . Her sister soon left the planet when she was able . She asked Ishara to come with her , but she refused – she had already joined the Coalition and considered them her family . She would always consider Natasha a coward for leaving , and would never see her again . Over the next several years Ishara would gain extensive knowledge about the tunnel system in the colony . In 2367 , the came to Turkana IV to rescue crew members who had escaped from the " Arcos " after a warp core breach . The Turkana IV Alliance had captured the two crew members and were holding them hostage in exchange for weapon s . Ishara volunteered to help the " Enterprise " - D in its rescue mission as part of a Coalition plot . She supplied the " Enterprise " - D with the location of the crew ' s escape pod , maps of the Alliance tunnels , and ultimately volunteered to create a diversion by setting off the Alliance proximity detector s so that Geordi La Forge could track the missing crewmen . She was stunned by a phaser blast , but Commander Riker brought her back safely to the " Enterprise " - D . Ishara also appeared to grow close to the " Enterprise " - D crew ( Lieutenant Commander Data in particular ) and indicated she wanted to leave the Coalition and perhaps one day join Starfleet . She also asked about Natasha and , after hearing about her , appeared to change her mind about her . Doctor Crusher removed the implant that identified her with the cadre and she agreed to accompany the away team on a second mission to recover the " Arcos " crew . This time , she would not set off alarms . However , once in Alliance territory – deeper than she could ever have gotten with the implant – Ishara took the opportunity to sabotage the fusion reactor that powered the Alliance defensive systems in order to enable a massive invasion by the Coalition . Data and Riker intervened by stunning Ishara so she could not shut down the reactor . Captain Picard , reflecting that they had all wanted to see more of Tasha in Ishara than had apparently been there , ultimately sent her back to her cadre instead of holding her for endangering Starfleet officers . As she left , however , she told Data that the time they had spent together was the closest thing to friendship that she had ever known . ( ) Apocrypha . Although she has not appeared in other media , in the novel " Q - Squared " , when the actions of Trelane cause three alternate realities to collapse into each other , Worf convinces an alternate Tasha Yar to help him escape " Enterprise " crew members from a third timeline where the Federation is at war with the Klingons by telling the alternate Tasha that Ishara regretted all the unhappiness between them , demonstrating a personal knowledge of her that convinces the alternate Tasha to trust him .