Battle Lines ( episode ) A runabout carrying Kai Opaka crashes on a planet of eternal war , where it is impossible for the combatants to die . Summary . Teaser . Jadzia Dax and Miles O ' Brien tell Benjamin Sisko about finding the personnel files kept by the previous DS9 prefect . O ' Brien tells Sisko he should probably warn Kira Nerys about her file before she can see it . Kira walks in at that moment and asks what should she be warned about ; Sisko tells Kira she might find her file disappointing , and Kira assures him she can handle it , and begins to review her file . Moments later , Kira storms out of the room , angry and insulted at how little emphasis she got as a member of the Bajoran resistance . In the meantime , Julian Bashir tells Sisko that Kai Opaka , who has never left Bajor before , is aboard for an unannounced visit and wishes to have the tour of the station that previously Sisko offered her . As they show her around the station , though , Opaka seems unusually distracted , which is noticed by Bashir . Sisko then notices Opaka standing by the viewport where the wormhole can be best seen . It ' s obvious she would like to see the wormhole , but doesn ' t say it . Since there ' s nothing scheduled to go through that day , Sisko decides to take her himself on a runabout accompanied by Kira and Bashir . O ' Brien prepares the , though , interestingly , as they board Opaka pauses to give O ' Brien a necklace she was wearing and asks him to give it to his daughter for her . He sees them off , a bit puzzled . Act One . Sisko takes the " Yangtzee Kiang " through the wormhole , and Opaka is amazed by the spectacle of the inside . Sisko remarks that she ' ll see in a few years just what it is worth to Bajor , and is ready to head back . Opaka , who is seemingly waiting for something , is disappointed until they pick up a narrow band subspace signal and insists they investigate it before leaving the Gamma Quadrant . They identify the source as a planet orbited by artificial satellite s , one malfunctioning . Bashir identifies a habitable moon with possible lifeform s when suddenly one of the satellites comes near the runabout and fires . The runabout loses control and they crash land . On the planet ' s surface , Sisko , Bashir , and Kira leave the runabout , carrying out the body of the Kai . Unfortunately , Bashir eventually pronounces the Kai dead , and Kira mourns . As they stand by the runabout , they realize they are not alone . Act Two . Meanwhile , on DS9 , it ' s been long enough that O ' Brien and Dax prepare the to find the crew . Odo must handle the frequent messages from Bajor on the Kai ' s status , as they were informed she went into the wormhole . He can only tell them they have a lead on where they are at the moment . On the planet , the crew is taken by the Ennis , a humanoid species , and they escort them into the cave s with weapons in hand . They are obviously cautious of them . The apparent leader , Golin Shel - la , is suspicious , but Sisko is able to convince him they are not hostile . He permits Bashir to help Kira with her wounds . He explains that they live along with their enemies the Nol - Ennis on the moon , which serves as a penal colony to which both groups were banished after their homeworld ' s mediators were unable to negotiate peace between the two factions . Now that the Starfleet crew is with them , they will be considered their allies and in danger , even though a rescue team is probably on the way . The Nol - Ennis suddenly attack the area and the prisoners immediately start the firefight . Several soldiers are killed from each faction before Kira puts an end to the skirmish by bringing down part of the cave ceiling , despite Sisko ' s desire not to get involved . Just then , the silhouette of the Kai unexpectedly appears in the cave entrance . She is alive . Act Three . Bashir examines the Kai , who appears normal and healthy . She says she only remembers the crash , but then nothing . She gets up and walks to see the area . Bashir further says her physiology is radically different , with an inexplicable biomechanical presence in her cells . He needs to do a full analysis to see what ' s going on . Interestingly , the other fallen soldiers similarly begin to revive . Fortunately , O ' Brien and Dax are able to trace the " Yangtzee Kiang " ' s warp eddy current to the system , and head there , though it is uncharted . O ' Brien is confused that they aren ' t even picking up the ship ' s transponder signal , which will make the search difficult . Bashir sees that the same phenomenon in Opaka is the same in these prisoners . Somehow , the transformation has kept them from dying . Shel - la admits that he has " died " many times before . Bashir wants to get the runabout ' s computer working to figure this out , but Sisko says it ' s too dangerous . Shel - la wants the answer himself , so he guarantees his protection and Bashir leaves . Opaka questions Shel - la on why the war started , but it ' s clear they don ' t care , they still want vengeance . It appears that they were sent to the moon as an example for the rest of the population on what happens when two sides can ' t come to a peace . The whole moon was designed to prolong their suffering . Kira , needing a defensible area , questions Shel - la about the Ennis ' lack of defenses . He responds that since both sides have realized that they cannot die , their tactics have changed . Sisko suggests that a Starfleet rescue team might be able to transport both of the factions to different planets , where they could live separately instead of continuing their endless fight . He challenges him to talk to the other leader to get a truce in the meantime . Act Four . In the meantime , O ' Brien and Dax find that they can ' t trust their sensors due to delta radiation . They ' ll need to search one planet at a time , but O ' Brien comes up with a design for a differential magnetometer which , fitted onto a probe , should detect the particular magnetic resonance traces in the " Yangtzee Kiang " ' s hull . This should speed up the search , though Dax is skeptical . Eventually , it works and they are headed to the moon . The Ennis and the Nol - Ennis agree to meet at a neutral site near the runabout . Sisko leaves with them , but Kira stays behind with Opaka . When they leave , she starts a conversation with Kira about her possibly seeing herself in these hardened people , having fought for so long and delivered so much violence . Kira initially doesn ' t see the parallels , but Opaka detects the guilt Kira feels for the violence she committed during the Occupation of Bajor . She says Kira must accept the violence within her in order to overcome the guilt , and comforts her . Kira admits she is afraid the Prophet s won ' t forgive her for what she has done , but Opaka says they are simply waiting for her to forgive herself . Bashir returns to the runabout , protected by the Ennis , to repair the computers so that he can investigate the artificial microbe s , or nanite s , further . He is successful and starts the computer to analyze the data . Soon , Sisko and the Ennis arrive . The Nol - Ennis leader , Zlangco , steps up to them and Sisko explains the deal . Unfortunately , neither side takes the negotiations seriously and the fighting breaks out again , with the Starfleet crew in the middle of it . Bashir pushes Sisko out of the way of a weapon that was coming towards him , claiming that they can ' t afford to die here , not even once . Act Five . Dax finds Human life signs on the moon , but O ' Brien , upon seeing the satellite system , realizes that it must be using a dampening field to block the " Yangtzee Kiang " ' s transponder signal , the reason he wasn ' t detecting it before . They retreat to a safe distance and he works on getting a communication through . Bashir explains to Sisko that the biomechanical devices that bring the Ennis and the Nol - Ennis back to life cannot survive in any other environment besides that of the moon . Furthermore , once a person has died with them , the body becomes dependent on them , meaning none of the Ennis , nor Kai Opaka , can ever leave again . O ' Brien then cuts in to signal Sisko , and lets him know he ' s working on a plan for transport . The satellites are going to make it difficult . Sisko goes to inform Opaka of her fate , however , before he gets to it , Opaka declares she is staying . With a moment of clarity , she believes that she has found the answers to her own prophecies . She says that , even as they came through the wormhole , she sensed that she would not return . She asks Kira to tell the others that she has answered the call of the Prophets , and that she was brought there because it is time for the people on the planet to begin their healing process , just as Kira was brought there to begin hers . O ' Brien manages to find a way to beam the marooned crew away by distracting one of the satellites with a probe thereby creating a hole in the defense grid established by the satellites . Informing Sisko , they start on it . Meanwhile , Bashir suggests finding a way to reprogram the microbes so that they would stop functioning after death , allowing the inhabitants to die for good and end their torture . However , when Shel - la expresses his intent to use it in order to defeat the Nol - Ennis for good , Bashir disappointingly abandons the idea . Fighting erupts outside and Shel - la is reluctantly drawn away . Sisko begins to tell the Kai that if they ever find a way to get her off the planet without killing her then they ' ll return , but Opaka interrupts him and tells him that her work is now on the moon . However , her and Sisko ' s " pagh " will cross again . The crew are beamed up leaving the warring Ennis and Nol - Ennis behind , and the Kai with a lot of work to do . Memorable quotes . " " You might want to warn Kira before she sees her file . " " ( Walking in ) " " Warn me ? About what ? " " " " Oh , uh , Dax and Mr . O ' Brien discovered some of the last Prefect ' s personal files . There ' s a file on you , but you may find it disappointing . " " " " I ' m a big girl , Commander . " " ( Later , storming out ) " " ' A minor operative whose activities are limited to running errands for the terrorist leaders ' ? ! " " " " Major , when you ' re through feeling under - appreciated , perhaps you ' d join me in welcoming the Kai aboard . " " " " Please , Commander . I don ' t get out often . " " " " The magnetic deflection of a runabout ' s hull is extremely weak . The probes will never be able to detect it . " " " " They will if I outfit them with a differential magnetometer . " " " " A differential magnetometer ? " " " " Mm - hmm . " " " " I ' ve never heard of a differential magnetometer . How does it work ? " " " " I ' ll let you know as soon as I finish making one . " " " " I ' ve discovered we can ' t afford to die here . Not even once . " " " " Nice work , Julian . " " " " When you cease to fear death the rules of war change . " " " " Opaka , if we can ever find a way . . . " " " " My work is here now , Commander . But your " pagh " and mine will cross again . " " Links and references . References . airlock ; Alpha Quadrant ; antimatter pod ; artificial microbe ; artificial satellite ; asteroid belt ; attitude control ; Bajor ; Bajoran ; Bajoran death chant ; Bajoran prophecy ; Bajoran transport ; Bajoran wormhole ; binary star system ; bio - pattern ; Cardassian ; cease fire ; cell ; Celsius ; Class 2 probe ; crash landing ; damping field ; ; day ; Deep Space 9 ; defense net ; delta radiation ; differential magnetometer ; directed - energy weapon ; ecosystem ; encryption system ; Ennis ; Ennis and Nol - Ennis homeworld ; Ennis and Nol - Ennis weapons ; Federation ; field triage ; flight stabilization ; forward thruster s ; fuel cell ; Gamma Quadrant ; gesture ; hour ; hull ; hull temperature ; hysteresis curve ; Idran ; Idran system ; impulse ; impulse generator ; induction field ; jailbreak ; Kai ; knife ; Kohn - Ma ; lifeform ; light year ; long range scanner ; magnet ; magnetic field ; magnetic resonance pattern ; M class ; mediator ; medical tricorder ; medkit ; megawatt ; meson ; metal ; Milky Way Galaxy ; minute ; moon ; mutual induction field ; nanite ; narrow band ; necklace ; needle in a haystack ; neuromuscular scan ; nightmare ; Nol - Ennis ; ; ops protocol ; orbit ; pagh ; palm beacon ; penal colony ; pendant ; phaser ; photon torpedo ; power reactor ; prefect ; Prime Directive ; probe ; Probe A ; Probe B ; Probe C ; Prophet ; pulmonary collapse ; punishment ; rescue team ; ; runabout ; runabout pad C ; second ; secondary booster ; sector ; sensor ; shields ; shoulder ; space station ; square kilometer ; starship ; straw ; subspace ; subspace signal ; Tahna Los ; ternary star ; terrorist ; thoracic vertebrae ; thruster s ; tomahawk ; torture ; transponder ; unnamed asteroid belt ; unnamed moon ; unnamed sector ; unnamed star system ; Vayan horn fly ; war ; warp ; warp eddy ; week ; ; year