Ptolemy is a saint that follows the orders he is given. When the four bronze saints arrive along with Athena at the Sanctuary, he is there to greet them in disguise. At first he tells them what will be awaiting them inside the 12 temples. But as soon as they come into the vicinity of the Aries temple he reveals himself and attacks them with a shower of phantom arrows.

(Source: Saint Seiya Wikia)