The arrival of the Traveler, for all the good it brought to Sol, painted a target on the entire system. Humanity has faced enemies from all corners of the universe: the Fallen, the Hive, the Scorn, the Vex, the Cabal, and the Taken, to name a few.
While Guardians successfully fought off each onslaught, a greater enemy was revealed: the Witness. A mysterious voice in the Darkness that led our enemies to our solar system and the Traveler. Though the Witness was cloaked in mystery, one thing was clear: it sought the destruction of the Traveler.