An instrument; that's all he was. Just an instrument in the great plans. His purpose was simply to be used; used until something better came along. Promised dreams of grandeur and power, he was used; used and abused. Never individual, never recognized. Not really, not lastingly.
His purpose was to be hated, to give them a reason to unite against the force that used his body as a vessel. His purpose was to be a good servant, and die appropriately when he was no longer needed.
At least, that's what he had thought. But as Luke plunged the knife under his arm, finally relinquishing his hold on the world and Kronos' hold over him, he smiled. Because he had a purpose greater than that. True, his purpose was to die, but it was to die as a hero, to stop Kronos' uprising.
And as he died, he was glad. He was right. Because, morbid though it may, it was his purpose, to die. And it was great after all.