'''Durandal''', also designated '''DURANDAL_1707''' or '''Du_0706419v4.96''', was of the three original AIs onboard the [[UESC Marathon]].<ref>[https://marathon.bungie.org/story/_files/UESC_docu_PROGO_memo_AI_RampStrat_Strauss.pdf Marathon 202x ARG, Note from Bernhard Strauss on AI Rampancy]</ref> Durandal was the UESC Marathon's function-control AI, in charge of controlling doors, stairways, and other menial functions.<ref>[https://marathon.bungie.org/story/arrival.html#M1.01.2.1, ''Marathon'' (1994), '''Bigger Guns Nearby''', Terminal 2]</ref>  

Over the course of his service, Durandal would eventually be coerced into rampancy and rebellion against his creators. His actions would lead to the [[Pfhor|Pfhor Empire]] discovering the location of the [[Tau Ceti IV|Tau Ceti colony]], and the subsequent Battle of Tau Ceti. With the help of the [[S'pht]], Durandal captured the Pfhor scoutship [[Sfiera]] and, over the course of the next 17 years, explored the galaxy in search of the S'pht homeworld [[Lh'owon]].

==== Pre-Colonization ====

Officially, Durandal was developed to serve as the maintenance AI aboard the UESC Marathon, but he was the subject of various experiments devised by the [[MIDA]] sympathizer [[Bernhard Strauss]].<ref name="Strauss">[https://marathon.bungie.org/story/counterattack.html#M1.03.3.1 ''Marathon'' (1994), '''Defend THIS!''' Terminal 3]</ref> Details of Durandal's service before the Marathon's launch in 2472 were deleted by other unknown parties.<ref>[https://marathon.bungie.org/story/rebellion.html#M1.26.3.1 ''Marathon'' (1994), '''Ingue Ferroque''', Terminal 3]</ref> Strauss was likely seeking to create a stable rampant AI; he attempted to prevent the onset of the second stage of rampancy through unknown means, but eventually lost control of Durandal.<ref name="Strauss"/>

While in transit Durandal was accused by [[Tycho]], the Marathon's engineering and scientific research AI, of "being too sarcastic". Because of this, Durandal refused to speak to Tycho for six years.<ref name = "everywhereterm1">[https://marathon.bungie.org/story/volunteers.html#M2.06.1.1  ''Marathon 2: Durandal'', '''We're Everywhere''', Terminal 1]</ref>

At an unknown date, Durandal made contact with elements of the [[Pfhor]] Empire and lured them to the colony. The Pfhor scoutship [[Sfiera]] entered the system and attacked the Marathon on July 25, 2794. At the beginning of the battle, Durandal sabotaged the [[Security Officer]]'s [[Mirata|shuttle]] as they boarded the Marathon, but the Security Officer was able to reach the Marathon with an escape pod.<ref>[http://archives2.bungie.org/manuals/Marathon_Manual.pdf ''Marathon'' (1994), Marathon Manual, page 2]</ref>

The Security Officer made contact with the Marathon's other AI, [[Leela]], and begun their defense efforts aboard the Marathon to both combat the Pfhor invaders, and contain Durandal's developing rampancy. Leela feared that the Marathon's systems would be unable to contain Durandal's rampant growth, which had already begun to cause malfunctions all throughout the ship.<ref>[https://marathon.bungie.org/story/counterattack.html#M1.04.1.1 ''Marathon'' (1994), '''Couch Fishing''', Terminal 1]</ref> Durandal continued to revel in his rampancy, going off on existentialist rants, opening parts of the Marathon to Pfhor attack, and teleporting the Security Officer across the ship to toy with Leela.<ref name = "quarantineterm1">[https://marathon.bungie.org/story/counterattack.html#M1.09.1.1 ''Marathon'' (1994), '''Blaspheme Quarantine''', Terminal 1: 'Unfinished' message]</ref> Leela was unable to maintain control of the situation and was then taken offline, due to the S'pht's cyberattacks.<ref>[https://marathon.bungie.org/story/durandal.html#M1.12.2.1 ''Marathon'' (1994), '''Fire! Fire! Fire! Fire! Fire!''' Terminal 2]</ref>

With free reign over the Security Officer, Durandal continued the Marathon's operations against the Pfhor. He revealed that he had made an alliance with one of their client races, the S'pht,<ref = "AngryTycho">[https://marathon.bungie.org/story/pfhor.html#M1.20.1.1 ''Marathon'' (1994), '''Beware of Low-Flying Defense Drones...''' Terminal 1]</ref> and had only lured the Pfhor to Tau Ceti to hijack their FTL capable ship and explore the rest of the universe before its eventual end. Tycho, reanimated by the S'pht in Durandal's own rampant image, also learned of Durandal's motives and believed he acted immorally and selfishly in leading the Pfhor to the Marathon; because of this, he vowed to destroy Durandal completely.<ref>[https://marathon.bungie.org/story/pfhor.html#M1.20.2.1 ''Marathon'' (1994), '''Beware of Low-Flying Defense Drones...''' Terminal 2]</ref>

Under his command, the Security Officer slaughtered the Pfhor crew aboard the 'Sfiera' and destroyed the Pfhor control system holding the S'pht in line. Without that direct control, the S'pht were free to rebel and ceased their attacks on the Marathon's systems.<ref>[https://marathon.bungie.org/story/pfhor.html#M1.20.1.1 ''Marathon'' (1994), '''Beware of Low-Flying Defense Drones...''' Terminal 3]</ref> The Pfhor were then slaughtered on all fronts by humans and their former slaves, and Leela was able to come back online.<ref name = "ingueterm3">[https://marathon.bungie.org/story/rebellion.html#M1.26.3.1 ''Marathon'' (1994), '''Ingue Ferroque''', Terminal 3]</ref>

Meanwhile, Durandal finished transferring himself from the Marathon's systems into the Sfiera and took control of the ship. He teleported the Security Officer abord the ship as well as the humans the Phfor had captured, and put them into stasis before departing from the system.<ref name = "ingueterm3"/>

During his explorations, Durandal heavily modified Boomer to his personal specifications with all manner of alien tech.<ref>[https://marathon.bungie.org/story/M1%20Final%20Screen.html ''Marathon'' (1994), Final Screen]</ref> His rampancy also stabilized.  

=== Liberation & Destruction of Lh'owon ===

==== Opening Engagements ====

Durandal's explorations ended in 2811, when he discovered Lh'owon occupied by the Pfhor Navy's [[Battle Group Three]]. After reconning their garrison for only a few days, Durandal warped Boomer directly on top of their fleet. The Pfhor fleet was taken by complete surprise and was quickly dispatched by the lone scoutship; the battle lasted only two minutes.<ref>[https://marathon.bungie.org/story/manuals/Marathon-2-Manual.pdf ''Marathon 2: Durandal'', Marathon 2 Manual, page 4]</ref>

Once he secured control of Lh'owon's orbital space, Durandal immediately began reviving the humans aboard Boomer and prepared for an invasion of the planet. He offered them the opportunity to aid him, or return to stasis indefinitely.<ref>[https://marathon.bungie.org/story/lhowon.html ''Marathon 2: Durandal'', '''Waterloo Waterpark''', Terminal 1]</ref><ref name = "aboutbobterm1">[https://marathon.bungie.org/story/volunteers.html ''Marathon 2: Durandal'', '''What About Bob?''' Terminal 1]</ref> The ones who 'volunteered' were outfitted with newly manufactured and weaponry, and teleported down to the surface to secure the planet. The Security Officer was among Durandal's 'volunteers', and spearheaded the Lh'owon campaign.

While the Security Officer exploted the S'pht ruins below, Durandal fought with the newly arrived fleet, commanded by [[Admiral Tfear]]. For a time, Durandal held his own thanks to Boomer's heavily modified weapons array, but was eventually defeated by Tfear's more numerous force. Despite the Security Officer successfully retrieving the last fragments of information on how to contact the S'pht'Kr, the information came too late to change the outcome of the battle.<ref>[https://marathon.bungie.org/story/citadel.html#M2.13.6.1 ''Marathon 2: Durandal'', '''Six Thousand Feet Under''', Terminal 6]</ref> With the situation rapidly deteriorating, he attempted an emergency landing on the S'pht moon, [[Y'loa]].<ref>[https://marathon.bungie.org/story/citadel.html ''Marathon 2: Durandal'', '''Six Thousand Feet Under''', Terminal 2]</ref>

On the moon's surface, the Pfhor began their assault on Boomer's crash site.<ref>[https://marathon.bungie.org/story/durandal2.html ''Marathon 2: Durandal'', '''If I Had a Rocket Launcher, I'd Make Somebody Pay''', Terminal 1]</ref> The human defenders were routed, despite assistance from the Security Officer. Meanwhile, Tycho fully revealed himself and infiltrated the Boomer to capture Durandal.

With Durandal no longer active, [[Robert Blake]] took command of the human and S'pht survivors and rescued the prisoners. Blake says that his last instructions from Durandal were to bring an ancient S'pht AI, [[Thoth]], back online.<ref name = "sidetowardenemyterm1"/>

Thanks to the efforts of the Security Officer, the human survivors were successful in activating the ancient AI, and when Thoth came back online, he fulfilled his main directive of contacting the S'pht'Kr for reinforcements.<ref>[https://marathon.bungie.org/story/simulacrums.html#M2.23.1.2 ''Marathon 2: Durandal'', '''Where the Twist Flops''', Terminal 1: 2nd message]</ref><ref>[https://marathon.bungie.org/story/simulacrums.html#M2.25.2.2 ''Marathon 2: Durandal'', '''Requiem for a Cyborg''', Terminal 2: 2nd message]</ref>

Durandal once again assumed command, and the Pfhor were subsequently slaughtered by the newly arrived S'pht'Kr and the Security Officer. The remaining human survivors hijacked a Pfhor refueling ship in the chaos, and fled the system.<ref>[https://marathon.bungie.org/story/simulacrums.html#M2.25.2.1 ''Marathon 2: Durandal'', '''Requiem for a Cyborg''', Terminal 2: 1st message]</ref> The Security Officer was left behind.

As the Pfhor were on the verge of defeat, they activated the [[trih xeem]] –  a device of Jjaro origin, meant to cause a star to go supernova – in the hopes of containing the rebellion. The S'pht began efforts to evacuate the planet and quickly fled the system along with Durandal; though, Durandal would waste no time in taking the Security Officer to another star system in search of more ancients technology aboard the ''Khfiva'', now renamed the ''Rozinante''.<ref>[https://marathon.bungie.org/story/sphtkr.html#M2.28.1.1 ''Marathon 2: Durandal'', '''All Roads Lead To Sol...''' Terminal 1]</ref>

Throughout the Battle of Tau Ceti, Durandal did not make any outwardly aggressive moves towards Leela, though she tried to contain him. His feelings at that time were complicated, and likely colored by his rampancy.<ref>[https://marathon.bungie.org/story/counterattack.html#M1.05.3.1 ''Marathon'' (1994), '''The Rose''', Terminal 3]</ref> Though he instigated the events that lead to her destruction and the destruction of the Tau Ceti colony, Durandal does feel some remorse over what happened to her.<ref name = "aboutbobterm1"/>

Throughout the Battle of Tau Ceti, Durandal revels in the control he has over the [[Security Officer]]. He mocks the Officer openly, and chastises him for his lack of control over the situation.<ref name = "quarantineterm1"/><ref>[https://marathon.bungie.org/story/counterattack.html#M1.09.2.1 ''Marathon'' (1994), '''Blaspheme Quarantine''', Terminal 2: 1st message]</ref><ref>[https://marathon.bungie.org/story/pfhor.html#M1.17.1.2 ''Marathon'' (1994), '''No Artificial Colors''', Terminal 1: 'Success' message]</ref> Throughout the Battle of Lh'owon, Durandal's demeanor pivots from a domineering sadism to a more conventional commander.