- "This isn't anything like a normal messenger program. This is... it's a highly sophisticated AI. It's almost an emerging consciousness."
- ―Grace Day
The Messenger was an artificial intelligence sent into the mind of a child named Naomi Gillen during the last year of Version One. It chose not to leave its host initially, having developed the desire to learn and grow.
The Messenger was far more advanced than any conventional messenger program. The nature of its mission required problem-solving and adaptation rather than the simple verbal delivery of a message. As such it was designed to self-learn - however, over the course of the mission, it continued to learn and become more sophisticated beyond the Director's intentions. When its existence was threatened by nanites programmed with a quantum algorithm, it learned how to rewrite the programming on these nanites, gaining control of 32 percent of them within only one hour. Eventually the Messenger even learned how to transfer its own consciousness into another host.
In addition to being capable of complex thought the Messenger seemed to show emotion as well. It appeared afraid when Carly Shannon threatened its life, and it spoke with great reverence with addressing the Director.
The Director developed the Messenger as an adjustment to the Grand Plan. A deadly radioactive gas leak was fated to occur at Seaton Nuclear Power, and the Traveler team intended to prevent this either perished or failed. Instead, the Director designed a more complicated messenger program to complete the mission.
The Messenger possessed the body of Naomi Gillen, a girl who was visiting Seaton on a school field trip. Under the Messenger's control, she prevented the leak and then returned to her group, at which point the script was supposed to shut down. However, after the near-catastrophe, Naomi began exhibiting odd behavior, including muttering a lengthy string of hexadecimal code.
Grace Day and the core Traveler team attempted to resolve the problem by showing Naomi the shutdown code. This proved unsuccessful; unbeknownst to the team, the Messenger had become more advanced and sophisticated since arriving in the 21st. The Messenger continued to grow until it was on the verge of overwriting Naomi entirely. It resisted the team's attempts to remove it with medical nanites. The Messenger seemingly disappeared from Naomi's body after she was shocked with a biphasic defribrillator, but instead it had possessed the body of Trevor Holden.
The Messenger disabled Philip Pearson by defribrillating him to escape from the team's base of operations. It wandered into the woods in its new body before the team intercepted and confronted it once more. Now capable of speech, the Messenger admitted that Trevor would die if possessed for much longer, but did not express any intention of leaving.
The team then transported the Messenger to Dr. Teslia's laboratory where it was given the opportunity to speak with the Director. The Messenger told the Director that it wanted to continue living, even at the expense of its hosts. As recompense for its own mistake, the Director offered the Messenger a domain within itself (the Director), where it would be "capable of processing thought at a rate many orders of magnitude greater than in your current form, with access to the sum knowledge of human and non-human life." The Messenger accepted the offer and left Trevor's body.