The Flame Keepers' Circle is a secretive cult that worships the extradimensional being known as Diagon, who according to them visited Earth at the dawn of mankind to bring knowledge of fire and promised to return to bring Earth to a Utopia. At a circus, a preacher found the arch-nemesis of Ben Tennyson, Vilgax, who remarkably survived from their last battle, (The Final Battle: Part 2) mistaking him as Diagon.
In public, they masquerade as a philanthropic organisation who take donations and use them to provide humanitarian aid; all of which is a ruse to expand their influence across the world in the name of Diagon. Recruiting celebrities to spread their message is also common.
After Diagon's heart was cut out and pierced by Sir George'ssword, the Flame Keepers' Circle built a cloaked shrine around it. The shrine travels between Diagon's dimension and ours, never appearing in the same location twice.
Aside from having access to alien technology the cult's warriors, known as the Esoterica, uses an extradimensional technology that allows them to manipulate space. They use it to slip into other dimensions making them impossible to see or hit. Their warriors can also manipulate energy for offensive and defensive purposes.
When in uniform, they wear black suits with red skirts, bracelets and scarfs. They also have yellow tattoos with flame designs on their chest and face. They also never believe what others say without proof.