The Traveler Phenomenon is the an extremely rare event in which one world or universe in the multiverse comes into contact with another, creating a small wormhole in which an unsuspecting person can fall into, resulting in their own displacement from their home world to another in a different place and time period leading to the untimely destruction of the world itself if the individual is not removed. These rare events most commonly result in the victim losing their clothing or other accessories not attached at a microscopic level, making them much easier for Guardians to find and rescue.
Often described with the analogy of bubbles floating through the air, ultimately coming into brief contact with one another, the Traveler Phenomenon serves as the premise for the Sem and Ally Adventure series. As universes move and exist along side one another, the chance of these worlds crossing paths can result in the displacement of a person in the wrong place and time period. Although it is not known what initially causes this rare phenomenon, it is theorized that the rise and expansion of civilizations among worlds plays a heavy part as humans discover new forms of technology that produce foreign energy, increasing the chance of worlds coming into contact with one another.
When an individual passes from one world to another, their foreign mass can leave a world unstable and on the verge of annihilation, like a bubble filled with air beyond its ability to hold. How long before the world itself is destroyed can vary depending on the stress humans have created on it or depending on the age of the world itself.
In some cases, war's and acts of human conflict can increase the likelihood of the Traveler Phenomenon as mass amounts of energy is being released into a universe which can expand a worlds reach to its neighboring worlds.
When a world is in danger however, a distress signal is created, which Guardians have used to lock on to a worlds location and send out a rescue team or individual with the goal of finding the person who doesn't belong and return with them to Asphodel, in turn saving the world from it's own destruction.