When the gods were torn from the Cunaerai by the hands of Fate and Time and placed outside of the mortal realm, not all were taken. Some minor celestial servants dedicated to the Light were left behind – whether by design or by accident it is not certain. Far from the power and proximity of their divine sovereigns, most of these celestial beings have diminished greatly in power, though they still strive to uphold the mandates of the Host of Day in their word and deed. These beings are collectively known as the aasimar – no longer true angels of Light but still vessels of purity and beacons of hope in a dark world.
These beings are rarely encountered, and scattered far and wide across the Three Lands. Though meetings between aasimar are typically warm and almost familial, they almost never travel together or linger in each others’ company for more than a few days. Most only spend enough time among their racial kin to exchange rumor and impart encouragement before separating and going their own way. Some say this is the mandate of Fate as part of the bargain with the gods of Day to allow them to linger in the Cunaerai unmolested by Her will.
Aasimar are immortal, though they typically ‘ascend’ when reaching a certain level of power or achieving an epic deed as presented to them by some god of Day or other. While wandering the Cunaerai, they prefer the company of those who strive for goodness and harbor honorable intentions, thought they will sometimes travel with those touched by Fate’s potential whom they feel can be redeemed or brought into the service of the Light.
Very, very few aasimar have succumbed to evil. Those who do shrivel and diminish like a rose in winter, never surviving their bleak turn of spirit for more than the passing of a season except through terrible magics or the dark charity of a god of Night. The Adversary and the Black Mirror actively court the downfall of individual aasimar.
Aasimar follow the racial statistics found on page 286 of the 5th edition DMG.