Achilles is..Heroic son of Peleus and the Nereid THETIS. He was moody, brooding, difficult... but a remarkable hero who got top billing in the Iliad. He was educated at the CHIRON School For Heroes and, to ensure his heroic status, mum THETIS held him by the foot and dunked him in the River STYX. The sacred waters bestowed all-over invulnerability, but his foot was unaffected. Thence ACHILLES's heel was the cause of his downfall, thanks to an arrow by the Trojan Paris.