Blazing Sun is an organization of elves who have converted to the Qun. They have many hidden shelters in the Tevinter Imperium and Seheron, and they shelter elven refugees and runaway slaves before sending them to Par Vollen.
The Blazing Sun appeared sometime in the Storm Age, during the Qunari invasions. Their original purpose was to protect refugees fleeing from the Qunari and to serve as elite soldiers for the Imperium during the wars. They fought many bloody battles against the Qunari, and they gained a fearsome reputation, along with a certain degree of respect, from the Qunari.
However, the magisters discovered that the Suns were helping runaway slaves escape the Qunari and declared them outlaws. Their numbers dwindled rapidly as their sanctuaries and shelters were torched. The surviving members of the order fled to Seheron, which was a key battleground in the war.
They built a small santuary in the forests of Seheron and began gathering all the survivors together. After months of relative safety, a Qunari patrol stumbled upon their shelter. The Suns, who were looking to avoid further devastation in their order, surrendered to the Qunari.
As they were being transported to the coast, a large force of Tevinter soldiers ambushed them, and the Blazing Suns saved the Qunari from destruction. After the skirmish, the Suns marched free with the Qunari, as opposed to being led away in chains.
The Qunari took the order to Par Vollen, where they stood before the Ariqun. He said they were honorable, but had also slaughtered many Qunari. Their only redemption stood in the Qun. The elven members of the order gladly converted, but the humans, who had strong faith in the Tevinter Chantry, were killed. From that point on the order was strictly elf.
They returned to the Imperium in secret and began setting up sanctuaries. They frequently ambushed slaver camps and freed the slaves, offering them peace in the Qun. Those who accepted were taken to sanctuaries, and those that refused were let go.
By the Dragon Age, the order had waxed strong. They grew throughout the years and had almost regained their pre-outlaw strength. They began openly appearing in battle alongside the Qunari, and soon the very sight of them inspired fear in Tevinter battalions.
Their headquarters are in an isolated area of Par Vollen, and their largest santuary and waypoint was their old hideaway in the forests of Seheron.