He was the only one who remained behind after the Big Fight. All of them disappeared during the ferocious attack... no one knew where were the others. They were the Warriors of the Past and everyone knew they were too dangerous... but now they were all gone. Finally they could live without fear, they could go on with their lives.
He wasn't dangerous, not at all. At first, they thought he would start fighting and taking over the warriors' place. They thought he was one of them, but he didn't do anything at all. He looked rather lost, without his fellows, but didn't seem to be looking for them or ask anyone where they were gone. Nobody knew anyway. He seemed rather relieved that they were not here.
Nobody knew who he was either, nobody has ever seen him around, or knew his family. He seemed to be a wanderer without a place of his own, without friends or family.