Mithrax, Kell of Light
Mithrax, Kell of Light (formerly known as Mithrax, the Forsaken) is a Fallen Kell and a former Captain of the House of Dusk who later founded the House of Light after deciding to ally with the The Last City, following an encounter with The Young Wolf.
Meeting with Sjur
At one point Mithrax, then a Vandal of the House of Wolves, was held in captivity by Sjur Eido. After a failed attempt at escaping her clutches and trying to commit suicide, Sjur befriends the captive Fallen by performing a traditional Eliksni display of armistice much to Mithrax's surprise. As they exchange names and Misraaks becomes Mithrax, he is introduced to the Dreaming City. Sjur becomes so renowned among the Eliksni they called her Siyuriks pak Variisis ("Sjur, the Unyielding") and forms an early alliance by giving Amethyst crystals as political gifts to their Archons.
Enemy Of My Enemy
After the SIVA Crisis, Mithrax would leave his wolf-born house and join the House of Dusk along with the remainder of his Fallen brethren. Guardians will encounter Mithrax and his crew in Chances and Choices as both parties compete to access an ancient methane reactor. Various Barricade Servitors and the High Servitor Selkis, the Obstructor are put in the way to prevent the Guardians from reaching the core, along with local Hive forces swarming the complex attacking both. Mithrax is later seen dueling against a Hive Knight in which Guardians are given a choice in who to kill. Killing the Hive Knight and sparing Mithrax will trigger an alternative ending in which he'll thank the Guardians with an Eliksni display of respect similar to Sjur's ages ago. He disappears and grants the player access to the reactor.
Alliance with the Guardians
While not physically appearing in Forsaken, sparing him is revealed to be the canon choice; Having been touched by Sjur's display of humility and the Guardians' mercy, he defects from the House of Dusk and swears allegiance to the Last City, eventually joining a fireteam of Guardians. He has also founded the unofficial House of Light to lead the more open-minded Eliksni as their Kell, arguing for the sake that humanity, not the Fallen, have proven befitting of the Traveler and its gifts. 
Later on, in the Season of the Drifter, Mithrax beckons Guardians to The Farm using a Fallen Transponder. Interacting with Mithrax takes both him and The Guardian to the Old Tower to complete the mission Zero Hour where they chase down House of Devils loyalists who have stolen preserved SIVA tech from a Cryptarch Vault deep inside. The group is in search of the weapon known as Outbreak Perfected, a Destiny 2 version of the famed Rise of Iron weapon, Outbreak Prime. Led by Siriks, Loyal to Eramis, the group is defeated before they could escape The Last City. After Siriks is defeated, Mithrax jumps onto a Fallen Skiff and once again disappears.
Mithrax sent vague reports to the Last City regarding activities occurring around no go area near Golden Age stations on Europa. He states there is "something that cannot be stolen from" which is a Eliksni reference to the Darkness as they "cannot take from the dark you can claim only pain".
List of appearances