Time Travel

Time travel is a person or object's movement away from the present time and to a different point in time in the past or the future.

The Methods of Travel
For someone to move through time, they must first abandon their body, becoming nothing more than a disembodied heart in the process. Xehanort accomplished this task by turning himself into a Heartless, allowing this incarnation of the man to make the travel necessary to begin the recruitment of the real Organization XIII.

The act of disembodying one's heart also allows the traveler to grant access to time travel to incarnations of themself scattered through different points of time. However, so long as these incarnations are not disembodied, they are unable to travel through time of their own accord, requiring assistance from the disembodied traveler.

The Laws of Time Travel
In order for one to travel to a certain point in time, there must be another version of them waiting at said destination. In addition, rewriting the events that are destined to happen is forbidden in the laws of time; what is set in stone cannot be changed. Upon return to one's original point in time, the traveler loses all memory of the experience gained traveling. In spite of this, the memories of these experiences are etched into the traveler's heart, which can potentially have an effect on their perspectives and decisions.

Terra-Xehanort
Terra-Xehanort is the body of Keyblade apprentice Terra's