Sylvie

The 2012 Loki, who escaped with the Tesseract during the time heist, is arrested by the TVA for creating a branched timeline. He's recruited by Mobius to hunt a variant of himself — Sylvie, who has been bombing the timeline for years.

How he controlled everything: he built the TVA, wrote its mythology, and then wrote a script. He had seen every branch, so he knew exactly what would happen and could set the machine running and step back. Loki and Sylvie arriving at his citadel was in the script.

Why does Sylvie kill him, and does Loki agree? Sylvie was taken by the TVA as a child and hunted her whole life, with one goal: destroy the organisation that stole it. Being offered stewardship of that same system is the one thing she cannot accept.

Season 2 — what the Temporal Loom is. The machine at the heart of the TVA that takes raw, chaotic time and weaves it into a single stable Sacred Timeline. It was engineered for one timeline. After Sylvie's kill, branches multiply infinitely; the Loom cannot weave infinite threads and moves toward a detonation that would destroy everything.