Praedyth

Praedyth was a Warlock who had been part of Kabr's fireteam during their assault on the Vault of Glass. Praedyth himself was believed to be a myth; Praedyth's Timepiece and Praedyth's Revenge are the only pieces of evidence of his existence, until the Vanguard discovered a message coming from the Vault.

His fate is explored in the Story Mission Paradox. After fighting through Taken, the Guardian discovers Praedyth's corpse, long dead, trapped deep within the Vault of Glass.

If a secret area in the Paradox mission is triggered as the Daily Heroic, it is revealed that Praedyth still exists as a ghost, and that he originally worked for the Future War Cult using a custom made Ghost shell, known to players as the Intrusion Shell.

Quotes

 * Praedyth's fall isn't over… because it hasn't happened yet… and it will happen again.
 * "He skipped like a stone on time's ocean. This is what's left." - Unknown
 * "Welcome to the end of the Vex. Their "immutable" future."