The Reader
Desmond's mind had spent eight years in the Grey. In his time there, he was transformed into a being of light, calling himself "The Reader". The Assassin Layla Hassan entered the Grey via the Isu simulation device the Yggdrassil Chamber to find a way to slow the magnetism of the global aurora borealis device. Layla showed the Reader more possibilities and calculations based on timelines he had not explored. The Reader then told Layla she had a minute to live as the radiation from the chamber was killing her physical body. Layla then decided to stay in the Grey with the Reader and explore more timelines.