Seadragon
History
Descendant of a noble lineage that could be traced back to Atlan himself and blessed with a mutant physiology that enabled him to shatter boulders with his bare hands, withstand the intense pressure of the deep ocean and rise above the waves without suffocating, Lethrys was born with the proverbial oricalchum spoon in his mouth. Inquisitive and impressionable, he subscribed to the unpopular - nay, borderline heretical - view that Atlantis should not content itself with a tiny stretch of the wide ocean while Lander civilisation flourished above, that the great god Poseidon would look favourably upon expansion and - dare he say it? - conquest? After all, was Poseidon not the god of all seas? And as his chosen people, did they not owe it to their lord to spread his teachings far and wide? Surely he had gifted Lethrys and others with great power for a reason?
Of course, it was mostly just youthful bravado and hot steam - Lethrys had the means and consequently the desire to explore the world beyond the walls of Atlantis, yet his traditionalist family stubbornly held him back. They decided service in the Atlantean army would quell his hotheaded tendencies and impart some old-fashioned military discipline, all the while putting his considerable power to good use. By all accounts he acquitted himself well and the warrior's life certainly agreed with him, but ultimately did little to curb his outspoken views. In fact, it endeared him to other likeminded individuals, more fervent in their conviction - but more subtle in their displays of it. A heretical cult that called itself the True Sons of Poseidon. As cults went, they were pretty inconsequential - but they hoped a noble figurehead could change all that.
The one piece of evidence to support their claim of Poseidon's favour was the possession of an ancient oricalchum helmet known as the Mask of the Seadragon. The legend goes that the helmet was forged by Poseidon himself for his chosen champion and his chosen champion alone; any others who dared don the Mask would suffocate until it was removed or they died. While the helmet itself was probably a random curio looted from a vault somewhere, that part of the legend held true - and, shocking absolutely no-one remotely clued up on origin stories, Lethrys was the only one who could wear it without choking to death.
Not that the revolution ever really got off the seabed. All it took was one cultist getting a little too vocal after too much seaweed wine for the authorities to go knocking on doors and making pointed inquiries. Atlantis had quite enough uprisings for once century. Lethrys was detained for a time and questioned. After it was ascertained that he hadn't actually done anything illegal per se, merely donned a silly hat and attended a few rituals and ceremonies, he was released - and barred from military service. Having shamed his family name with his heretical ways, the disgraced scion left Atlantis to see the world - but he took the Mask with him.
He had a taste for adventure, as it turned out. After a year of aimless wandering, living off the land and leaving a trail of battered sharks, barbarian hordes and ancient sea monsters in his wake, he began to recieve strange dreams. It was always the same: swimming alone through a sunken city, but one that was far different to Atlantis. Empty winding halls reduced to desolate ruins, crumbling spires twisted into puzzling configurations that brought stinging tears to the eye that gazed upon them overlong. And the remains of silent, gape-mouthed statues that had precious little to do with the human form - and others, menacingly clutching stone tridents in their claws, with heads uncannily reminiscent of Lethrys' Mask. One more familiar sight always awaited him at the end of these dreams, after spending seemingly endless hours swimming through the dark: the briefest glimpse of a statue of Poseidon.