So the vanguard has some doctors and cryptarchs examine him. He's healthy, human, and the ghost didn't make a mistake. He's got a lot of light in him. They hand him off to a Warlock who turns out to be his father resurrected as a Guardian. He raises him, teaching him simple things. The tower is like his home and the people within his family. Then, one day, he got too curious. He found a way out of the city and guess which house captured him.