The Grey Sisters are the most powerful seers on earth. Nothing escapes their gaze, not even the minds of the Gods. Exactly whether there human or so kind of creature is unclear. They appear as very elderly women, with greatly deformed near featureless faces, they all share one eye, which they hand to each other to let them see.
Following Ariadne's poisoning by Medea, Jason along with Hercules and Pythagoras traveled to them, as they were the only beings who knew the cure. Expecting him, they were first unwilling to talk, however Jason stole there one eye and threatened to cut it in two unless they told him what he wanted to know. They revealed that the cure was Medea's own blood, however laughed at his suggestions of killing her, revealing the cryptic prediction that he would need her in the future or else all his work toward good would be for nothing. Having what he wanted Jason tossed the eye back to them, leaving them to search for it as he left. ("The Grey Sisters").
- Cosmic Awareness: As the most powerful seer's on earth, the Grey sisters possessed knowledge beyond all others, even the minds of the gods was not kept from them. They could see the future and the past, and where aware of the answer to nearly any question. However they did not know everything, as Jason was able to suprise them by stealing there eye, suggesting either while they know the outlines of everything, they don't know all the details. Or the rule of seer's being unable to see there own future also applies to them.