Hydros

Hydros (ハイドロ Hydro) is the King of Lemuria. He is an ally of Piers and a friend of Lunpa. Hydros knows about how Gaia Falls is eroding the world of Weyard, and he advocates lighting the Elemental Lighthouses to counter that, despite pressure from the Lemurian senate. He gives Felix the Grind Stone which the party uses to enter the Great Western Sea. He is the oldest of all the Lemurians, which we learn from a woman in Lemuria. He is referred to as "good King Hydros" by the Lemurians, and seems to be well-liked by his people, with the exception of the members of the senate. Piers describes him as "The oldest man who ever lived".

Story
Shortly after Felix's party arrives in Lemuria, they are welcomed into the palace to have an audience with King Hydros. Hydros is eager to hear their reports of the outside world, which he requires in order to confirm or refute his theories on the effects of sealing Alchemy. Namely, he theorised that Weyard was dying, as the lack of Alchemy to fuel the land's life would lead to its gradual decay. He was so concerned about the truth behind this theory that prior to the events of The Lost Age he organised for Piers to leave Lemuria and explore the world beyond the Sea of Time, as Lemuria's own knowledge was significantly out of date, seeing as no-one had left or entered Lemuira in over on a century (which was when Lunpa and Babi chanced upon the civilisation).

However, he met strong opposition in the Lemurian Senate, a powerful governing body that firmly held the belief that Alchemy was a dangerous power and the outside world was none of their concern. The argument between the two governing bodies raged and ultimately, no action was taken. The deadlock was broken whan a freak wave caused by Poseidon's return, coinciding with the lighting of the Venus Lighthouse, caught Piers and his ship and washed them out to sea, leading to his eventual detention (and subsequent release) by the folk of Madra. After some time, Piers, now travelling with Felix's party returnes to Lemuria, with enough information to confirm the king's theories. Even in the face of overwhelming evidence, Conservato, leader of the Senate, is flabbergasted and outraged to learn that two lighthouses have already been lit, and far from supporting the party, threatens to banish the party from Lemuria. Indeed, even though King Hydros openly supports the group, going so far as to give them the Grind Stone to help them accomplish their task, the Adepts, specifically Piers, are exiled from Lemuria forever (although in-game you may return as often as desired, as the banishment is perpetually held up in bureaucratic processes, preventing it from ever actually taking place). Thus, once Felix's party leaves Lemuria, King Hydros plays no further role in Golden Sun's plot.