Ghost Scan: The Rig, Titan, #3
Ghost: The Fallen need Servitors to provide them with Ether. Unless they've found a replacement, like SIVA. Gosh I hope there's no SIVA on Titan.
Lore — Ghost Scan: The Rig, Titan, #3
Ghost Scan: The Rig, Titan, #3
Ghost Scan: The Rig, Titan, #3 (transcript) - Destiny 2 (Red War) (2017)