From Destinypedia, the Destiny wiki
The Spectral Network was an organization of Ghosts who served the Vanguard of The Last City as scouts and spies in the fringes of the Sol System. The Ghosts who joined the Network were those who had yet to find their Lightbearer to revive and instead decided to serve the Light in other ways until they found their partner.
One member of the network, Wren, infiltrated a Fallen base and observed the ceremonies in which an Archon oversaw the elevation of worthy Fallen up the ranks of their House. However, Wren became careless while watching the ceremony and was spotted by the Archon. They frantically sent out a final message to the Vanguard as they attempted to escape, fearing that they were too deep within the base to do so.
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