A legacy is a person who inherits the memories of another who died before they were born. This occurs in one out of five hundred people in Uru, and the mechanism behind it is a mystery. Until they reach their sixteenth birthday, a legacy usually only experiences flashes and dreams of these memories; when they reach sixteen, the memories arrive as if they'd always been there, usually requiring quite an adjustment period.
Legacies have a higher probability of inheriting memories from someone who lived nearby than someone from another nation or the other side of the world. However, “foreign memories” are received often enough that governments tend to treat legacies as sources of information on foreign lands, even if that information is at least sixteen years old.