Thanatos
Thanatos has seen many things that the other Gods could not bear. He has seen his land shattered and strewn across Fou Lu. He has been captured by a Dragina; humiliated because he had to rely on mortals to save him. On top of that, the God of Dreams has witnessed every last horrible nightmare. He is a powerful concentration of thought, in his more vague description, and so has contemplated on every last miniscule thing. Perhaps this has made him go insane, or perhaps it has given him an insight the others simply don't understand.
The Psychic God, last created of the elemental rulers, has no race to call his own, as do his brothers. Nor does he possess the grace and beauty of his sister. He is humble, a lover of books and learning, not a warrior in any sense. Some think this makes Thanatos weak, but his control of magic makes any confrontation with him unpredictable. He prefers to remain isolated, rarely talking to his followers or visiting the small islands that are all he has left. Instead he stays in a realm of thought, sitting in a palace that bends to the whim of his mind.
So he sits now, and watches the events, each of which he inscribes in his great tome. He is the recorder of all the history of Fou Lu, and will continue to be so until it ends. Thanatos may not know what will happen in the distant future, but as it comes to pass, he shall see it on the horizon, and write it once it has happened, so that nothing will be forgotten. The other Gods do not know of these records, only Althena knows, for it is she that commanded that he write them. His siblings do not know the true power of Thanatos' magic, the spells he keeps locked away from mortal and immortal alike. This burden weighs upon him, greatest of all while he was held captive. He could have unleashed terrible power to free himself, but then others might learn of the spells, and he could not let that happen.
He is considered by many to be the weakest God, and not thought of as a threat by his siblings. Perhaps if the God of Knowledge loosed all of his secrets upon the world things would change. Still, Thanatos cannot do this; it is not in his character. He carries these things upon his own shoulders and does not complain. His strength may not be in war or strategy, but in endurance and stoicism. So it was, so it has been, so it is, so it will be. Thanatos knows his place in this world, and he continues to fulfill it, as he ever shall.