While he was still a Vandal in the House of Wolves, Mithrax was jailed by Sjur Eido. Sjur, who had some knowledge of the Eliksni language, was able to communicate with him.1
Based on his appearance during his first encounters with the Guardian, Mithrax likely became a member of the House of Dusk.2
Around the time of the Red War, Mithrax and other Fallen from the House of Dusk attempted to steal a methane reactor from a site on Titan.3 However, when confronted, Mithrax instead chose to hand the reactor over to the Guardian.2
Mithrax also formed a fireteam with two Guardians. While on a journey with them, Mithrax expressed a desire to unite the Eliksni under one banner.4 At some point, Mithrax founded House Light and became its Kell.5
Following her escape from the Prison of Elders, Eramis, who was still a Devil, hatched a plot to steal a SIVA weapon from the City’s old Tower. Mithrax became aware of this plot and alerted the Guardian, who traveled to the old Tower to recover the weapon.6 He also infiltrated the Devils’ heist in order to assist the Guardian in their mission.7
Prior to the House of Salvation’s formation on Europa, Vanguard intelligence released a report regarding a number of potential leaders of Fallen “reunification efforts.” One such possible leader was Mithrax, who was reported to be assisting Guardians in the field.5
In an intelligence report made before the Guardian’s journey to Europa, agent CHA-319 reported that Mithrax had relayed “vague reports of a taboo no-go area” around the BrayTech station.8
With the assistance of Variks and the Guardian, a number of Eliksni fled Europa to join Mithrax’s House Light.9 Variks expressed some doubt about Mithrax’s age and ability to lead, as well as the small size of his house.910 However, he still saw Mithrax as a symbol of hope for the Eliksni.11
In the past, Mithrax has been in contact with at least one of the Spider’s associates.12