Ouroburous.
It was simple enough – a snake biting its own tail, forming a ring. It was on all of them, marking them indelibly for what they truly were: fantasy creatures, running along the ring of life and death without truly experiencing either: for without one, the other cannot exist.
He knew this, and in dark moments wanted death, lusted after it. He might seem alive – had thought himself alive – but that had changed once he met the Elric boy. Saw him fighting fiercely – selflessly – for his brother.
How was it that even the younger one – no more than a soul in a suit of armor – could be more alive than he himself was?
He knew, from the moment he saw the armored soul, that he wanted what the boy had, but he never expected just what it was he wanted. He had thought that he wanted the seeming immortality granted to the boy: the chance to continue running forever along the ouroburous' back.
But really, it was the sheer vivacity of the boy, of both boys. They knew that they could die: and because of this knowledge, lived all the harder.
And he realized that what he wanted was not to continue running forever: he wanted to someday reach the serpent's tail, and have that great maw open in front of him, and devour him.
He wanted to die: because without darkness, there can be no light; and without death, there can be no life.
And he watched as he reached the serpent's tail one last time; finally, the great mouth of the ouroburous opened in front of him, and Greed finally, truly died with a serene smile on his face.