Immortals are people who were born in different intervals during history who have the impossibility of dying. This is the Eternal Curse, this curse was part of the creation of the world when humans became intelligent. Every so many thousand years a new immortal is born. Most immortals are magnets to each other and travel in packs of two. Some unlucky immortals are drawn to mortales.
Some mortals have an inner magnet that are connected to a certain immortal. Because they are mortal they will die but they are on a cycle of rebirth until the end of days or their immortal dies.