Destiny 2: What happened to Si-3
When the City was being assaulted, Semper Invicta was out in the wilds on a smash and grab operation. He tried to rush back and assist, but could not safely escape the Eliksni forces in the area. Instead, he began trailing back to find a means of locating his partner, Fenrir-10 and their fire team.
Once the Traveler’s Light had been drained and his own wrenched from his body, he collapsed in the snow to remain there for three weeks until discovered by an Eliksni scouting party. Thinking he was dead, the Captain ordered Si be brought with them back to their camp.
It wasn’t until they arrived that his body responded to the stimuli of being carried and his optics came back online. Unarmed and Lightless, Si-3 was at the mercy of the Eliksni. Fortunately for him, he fluently spoke their language and managed to broker a deal. He would repair and maintain their equipment and tech in exchange for the continuation of his life without unnecessary pain and torture. After what happened to him with the House of Devils, he wanted to be especially careful now that he was in no position to fight back.
Eventually he worked up enough trust with House Dusk that he was given a new cloak to wear, one that bore their sigil in white against a crimson cloth that still paid tribute to the stripes his armor bore. He still lives with the Eliksni and tends to their tech, but he longs to someday return to the City or, at the very least, see his friends and fellow Guardians again.
(Subject to change depending on Fenrir’s D2 verse information. <3)
((I’ll add this to his dossier as well))