Pyrefly Pyreflies are an ambiguous , naturally occurring phenomena that heavily influence the events of " Final Fantasy X " and " Final Fantasy X - 2 " . Pyreflies are prevalent throughout the world of Spira and are closely linked with the lifeforce of beings by being the form that disembodied spiritual energy takes . Despite the allusion their name gives to the real - world insect , pyreflies are not living creatures . Though they have been harnessed to many uses — both good and ill — in their inert form they lack self - awareness and any identifiable agenda . As such , they are but an aspect of nature . Nature . According to " Final Fantasy X Scenario Ultimania " , pyreflies are usually invisible , but can be seen when condensed in high concentrations . When a fiend is defeated , or when a summoner performs a sending , they glow and thus are often mistaken as " arising when there is a loss of life . " Pyreflies and water are said to harmonize easily . When a summoner performs a sending , the pyreflies on a water ' s surface can solidify into a foothold . The blitzball sphere pool utilizes pyreflies to congeal the water into a sphere . Blitzball players can stay active underwater for extended periods of time because they are supported by the pyreflies contained in the water . Pyreflies exist in one of three distinct states . When inert , they manifest as insubstantial points of iridescent light , similar to the fireflies from which their name is partially inspired , which float aimlessly within a particular area of attraction . Inert pyreflies generate a delicate sound . Concentrations of pyreflies can form physical creatures , yet remain insubstantial , creating phenomena reminiscent of ghosts . In the final state , pyreflies can take on the properties of solid matter . For example , aeons , Dream Zanarkand , and the body of Sin consist of vast quantities of pyreflies . Pyreflies can crystallize into spheres , much the same way the Mako energy in " Final Fantasy VII " crystallizes into Materia . This happens by the pyreflies reacting to people ' s feelings and memories and binding them with images and audio . Spheres make use of these properties of pyreflies to make recordings . The raw material for spheres is water that contains a high concentration of pyreflies , gathered from specific locations , such as the Macalania springs . In " Final Fantasy X - 2 . 5 ~ Eien no Daishō ~ " it is implied some people are more sensitive to pyreflies than others , and those especially keen to them can become summoners , able to manifest pyreflies into various corporeal forms . Pyreflies and death . When a person dies their body cannot simply be laid to rest : their spirit , or lifeforce represented by pyreflies , must be released from the body and given " guidance " to return to the Farplane , a place inside the planet where its lifeforce is gathered . A summoner is required to engineer this " guidance " in a ritual known as the sending . If the sending is not performed , the body ' s spirit is trapped in the physical plane , growing first envious , then hateful of the living . The hatred eventually grows strong enough to manifest one ' s pyreflies into a fiend , a fully substantial and dangerous monster . Not all of the recently deceased must be sent , but mainly those who have suffered a violent or untimely death . Yuna suggests that those who have accepted their death may naturally come to the Farplane , similar to legends of ghosts , as ghosts may linger and become malicious towards the living , but those who have accepted their deaths pass on to the other side . In some cases the dead do not transform into a fiend . If the deceased possessed a powerful will regarding an unfinished purpose in the world of the living , an individual ' s postmortem spirit can manifest their pyreflies into a physical form in the image of the deceased ' s former body . Such beings who may act and function for the most part as they did in life , are referred to as " unsent " and may be benign or malicious , depending upon the individual ' s nature . Fiends and unsent , as well as aeons , are sustained by the thoughts that caused their creation . For fiends , it is hatred and envy of the living . For aeons , it is the dream of the fayth , people who willingly gave up their lives to have their souls trapped in statues and exist in perpetual state of dreaming . For unsent , it is the unsent person ' s own strong will to remain in Spira . The unsent are usually unwilling to enter the Farplane using the gateways that exist in Spira . This is believed to be because they may be physically unable to leave , and are wary of taking the risk . They are vulnerable to the effects of the sending , which can banish the disembodied spirit to the Farplane and disperse their pyreflies , usually no matter how strong the will that binds them . There have been two notable exceptions : This likely occurred in these cases because the victims died " unclean " deaths ; it is said that those who die unclean deaths are the only ones who can leave the Farplane . Another exception to dying without becoming a fiend in the absence of being sent still results in one ' s spirit finding its way to the Farplane . One who accepts death while still alive will travel to the Farplane after death without assistance . This is seen in the cases of Tidus ' s mother and Yuna ' s father , the latter of who was high summoner Braska , a summoner who willingly gave his life in a battle with Sin . In addition , the unsent may voluntarily send themselves at will . The sending . The sending ritual transfers sentient lifeforce to the Farplane . The lifeforce , if any , of the flora and fauna are unaffected ( it can be inferred , in fact , that such wildlife , as well as the planet itself , draw energy from the lifeforce contained within the Farplane ) . Fiends , whose souls have been consumed by hatred , are subsequently not affected . A sending , therefore , is known to affect the following : During a sending pyreflies emanate not only from the dispersed " bodies " of the unsent , but also from the recently deceased . This indicates ( confirmed by the " Final Fantasy X Ultimania Omega " ) that pyreflies are always present in the bodies of the living , as well as in everything else in Spira . Pyreflies and the continuation of memory . The Farplane . Spirans have long enjoyed occasional visits to the Farplane , primarily using the gateway within Guadosalam , to call up their memories of those who have died . Since the Farplane is filled with pyreflies , some are attracted to the evoked memories and give them partial substance , forming a ghostlike image of the subject being recalled . The physical plane . The attraction pyreflies show to the energy of strong memories is not restricted to the Farplane , nor are the spirits of the dead necessarily required to manifest their spiritual energy to interact with the living on physical terms . It is possible to perpetuate a spirit ' s memories against their will , and in certain cases the dead may possess the living . When Yuna and her guardians travel to the ruins of Zanarkand they witness numerous memories of past summoners and their pilgrimage s via the local pyreflies . They witness a scene of Yocun and an unknown female guardian offering to become Yocun ' s Final Aeon ; Seymour and his mother on their way to obtain the Final Aeon ; and witness memories of Braska , Jecht and Auron ' s journey . On Yunalesca ' s throne the pyreflies display a memory of Auron attacking Yunalesca . One thousand years ago Shuyin was killed by agents of the Bevelle army while attempting to operate their super weapon , Vegnagun . Shuyin desired to destroy Bevelle , as he believed he would be unable to save his love , Lenne . Reunited before death , Shuyin didn ' t hear Lenne speak the words " I love you " to him before his life faded . Thus , his feelings of hatred toward Bevelle , and the feelings of self - loathing that emerged due to his perceived failing of Lenne , resulted in his spirit becoming full of hatred and despair . The " Final Fantasy X - 2 : International + Last Mission Ultimania " elaborates in its " Four Puzzles " section that the " Shuyin " who Yuna and others meet is not the original Shuyin , but his " shadow " full of the despair and hatred the Shuyin of 1000 years ago felt , preserved by pyreflies . Places where pyreflies are dense " remember " moments from the past and project them , and in the case of Shuyin , these " phantom thoughts " began acting on their own . The difference between Shuyin ' s shadow and a true unsent is that its pyreflies cannot interact physically . While Shuyin ' s shadow lacks physical substance , it can produce extensions of itself , and to influence the state of mind of those around it , as seen inside the Den of Woe . For it to physically interact with the living world the shadow needs to possess someone to act as its vessel . A suitable vessel would be someone in similarly despairing disposition who is strong both physically and spiritually . However , should the shadow ' s vessel lose consciousness , transferring to a new one is not possible . The powerful emotions emitted by Shuyin ' s blackened spirit attracted a multitude of pyreflies that became imprinted with his despair and painful memories and refused to allow them to fade , fusing with the pyreflies within the Den of Woe granting them a self - awareness . Shuyin ' s shadow possessed Nooj and used his body as a vessel , forcing him to critically wound his comrades on one occasion , and nearly forcing him to do so a second time two years later . Shuyin ' s shadow abandons Nooj and possesses his former comrade , Baralai , as a new vessel to operate Vegnagun . In certain cases those who have died can return to Spira , their bodies made manifest by the pyreflies . The first such case Yuna witnesses is Jyscal Guado when he exits the Farplane to hand her a sphere detailing his son , Seymour ' s , crimes . This is due to Jyscal ' s unclean death leaving his strong emotions seeking resolution . After the fayth go dormant and Tidus disappears from Spira , Yuna asks the fayth to return him at the end of " Final Fantasy X - 2 " , and Tidus is restored to Spira , although he still suspects being a dream of the fayth , i . e . made of pyreflies . In " Final Fantasy X - 2 . 5 ~ Eien no Daishou ~ " Tidus dies on an unknown island but Yuna beckons him back to life . It appears she is no longer the only one able to call things back to Spira from the Farplane , however , as more and more of the dead are manifested by the pyreflies by the memories of the living . Other appearances . Because pyreflies allude to " hitodama " , a part of Japanese folklore , the concept of life essence being depicted as glowing lights has also appeared in other games in the series . In " Final Fantasy VII " Lifestream is a glowing magical substance akin to Spira ' s pyreflies . The Espers ' crystallization animations in " Final Fantasy XII " have their bodies disperse into glowing Mist . In the " " series souls are crystal energy that can occasionally be seen by naked eye . " Dissidia Final Fantasy " . Whenever a Warrior of Chaos is defeated , a dark substance similar to pyreflies emit from their bodies before fading . This occurs for all Warriors of Chaos except Golbez and Sephiroth . Substance similar to pyreflies appears from a weakened Cosmos at the beginning of the prologue and of Shade Impulse . They also appear in the latter scene when the ten warriors of Cosmos fade one by one as a result of Cosmos ' s supposed demise . Pyreflies are also present in the stage Dream ' s End . " Dissidia 012 Final Fantasy " . All of the aforementioned appearances of pyreflies appear within Dissidia 012 . In Treachery of the Gods story line , Tidus , after taking the Emperor ' s hit to protect Yuna , begins to fade away and light pyreflies appear despite being a Warrior of Chaos , but disappear due to Jecht ' s light . Pyreflies appear in Yuna ' s EX Burst , To The Farplane , when she sends the opponent , during which they disappear in a shower of pyreflies . Pyreflies , or at least look - a - likes , were included on " Dissidia 012 Final Fantasy " official European teaser site moving across the site in similar manner like they rush in " Final Fantasy X - 2 " menus . Non - " Final Fantasy " appearances . " Kingdom Hearts " . In the " Kingdom Hearts " universe , when someone ' s heart has moved on , the body disappears in a flash of light that separates into orbs of light that float away . These specks of light resemble pyreflies . " " . During the Olympus Coliseum segment of the end credits scenes , Auron looks on as Hercules , Megara , Phil , and Pegasus admire the newly reconstructed stadium before returning to the Underworld , dissipating into pyreflies . The foursome notice this and see the pyreflies swarm the stadium . Etymology and symbolism . The word pyrefly is a portmanteau of the words pyre and firefly . Pyreflies are mainly seen in their inert stage upon a person ' s death , in the Farplane ( the realm of the dead ) and during a sending , which itself alludes to ancient Japanese funeral rites . Pyreflies refer to " hitodama " . Pyreflies transcending all existence in Spira relates to ism that posits a generative , immanent force harmoniously pervades the whole phenomenal world .