Surya is the eldest son of Mahadeva and Parvati and is the God of the Sun. He was the most powerful of Mahadeva's children, as without the Sun, all life in the Whorl would freeze and die. Surya, jealous of his father's power, began a rebellion that became the War in Heaven and Earth (see Ancient Lore). Ultimately, he slew his father but was in turn defeated by his mother and most of the other gods who combined their power to create the Ten Great Dragons to bring him down.
Surya could not be killed, however, as his power is still required to energize the Sun. Instead, he was chained in his Realm which became his prison along with his devoted followers. His prison is not absolute, however, and he still exerts some influence over the people of the Whorl. Greedy or foolish people with the right secret knowledge can open small portals into Surya’s Prison to gain the service of devils and demons who will at least appear to serve their summoners, but who really serve their master who seeks ever to escape and assume his rightful place as King of the Gods.
Surya is now commonly referred to as the Archfiend. Although his power is strictly contained, there are loopholes in the protocols. He can grant power to warlocks who manage to contact him and forge a pact capable of piercing the walls of his prison. Certain wizards have also mastered the arcane talents necessary to treat with him and his minions. His power is far too constrained, however, to effectively empower clerics or other divine spellcasters.
Surya was once depicted as a statuesque man nearly featurelessly bright with light. Now, when he's depicted at all, it is as a sinister figure bound in chains.