Medusa is the high priestess of Athena on the island of Kythra, whose deception by the vile Phaedon, who convinced her to disband the city guard, lead to the fall of Kythra. Medusa's own fall from grace lead to her transformation into a truly hideous creature comprised mostly of giant snakes. However, Medusa had retreated inside herself because of this, and fell to insanity, no longer aware of her hideous transformation and believing that she still resembles a golden statue of herself that Phaedon had crafted in her image to feed her vanity, which she holds tight, practically worshipping it, and refers to the statue as her "pretty pretty".
Medusa serves as the boss fight of Kythra in the game. She is defended by large snake-like tendrils which attack Jason and the rest of his party; Jason can batter the heads into submission, and Pan can then seal them outside of the room by meditating on the Virtues of Athena; once all the heads are sealed away, Medusa drops her golden statue. Jason must then pass judgement on Medusa by either sentencing her to death and killing her (by attacking Medusa) or granting her a reprieve and instead "killing her vanity" (by attacking the statue). When the statue is destroyed, Medusa's loving brother Perseus will arrive to show Medusa, with his mirror-reflective shield, that her vanity has made her ugly and monstrous, and the blow to her ego will restore Medusa to sanity, and more importantly, to her human form.
If Medusa is saved from the curse, she will agree to keep the needs of her people in mind as she leads them from then on, and will begin by accompanying Jason and his Argonauts as the representative of the bloodline of Athena, as requested by the Oracle of Delphi.
Medusa is one of the three gorgon sisters. Medusa is notable as being mortal, whereas her equally monstrous sisters Euryale and Stheno are immortal, and could never have been killed. All can turn someone to stone just by making eye contact, so the Greek hero Perseus (who was completely unrelated to the Gorgons) polished his shield to a mirror shine and looked at Medusa's reflection instead of actually looking at her. He successfully killed Medusa by decapitating her, and Pegasus the winged horse is said to have sprung fully formed from the pool of blood her head left behind.