Percy Jackson and the Olympians: Legends

Achilles is described as looking like the god of war, Ares; tall and buff with closely shaved black hair. What sets him apart from Ares was that his eyes looked human, being a shade of pale green, instead of hollow sockets filled with flames.

A modest hero, despite being a renowned Greek hero, Achilles is very humble and self-deprecating. He sees no reason to regale people with stories of his past. Unlike, for example, Theseus, he does not boast about the deeds that earned him fame. Achilles acts as emotional support for Zagreus, and becomes the "older male role model" for Zagreus. Achilles is cool, caring, a wise and noble mentor, and one of the few genuinely heroic heroes. Achilles is in charge and provides information and guidance about the Underworld and the gods of Olympus. Though not immediately apparent, it eventually becomes clear that Achilles is secretly tormented by guilt and self-loathing for the many atrocities he had both witnessed and committed while alive, especially when it came to the war with the Trojans, which also led to his death. Because of this, when questioned about the many battles he participated in, Achilles always refused to go into real detail.

Achilles was a hero of the Trojan War. He was the son of the Nereid Thetis and the mortal hero Peleus. Achilles was considered to be one of the greatest Greek warriors who ever lived, sometimes said to be the "shield of an army." He is most famous for being the first child to be dipped in the River Styx by his mother Thetis, making his body invulnerable to any weapon, except for the only part of his body that wasn't dipped into the river - his heel since his mother dipped him into the river by grabbing him by the heel. He was killed in the Trojan War by Paris of Troy, when the latter shot him in the heel with an arrow. As such, the term "Achilles' heel" had come to mean a fatal weakpoint, and the Achilles tendon is a tendon located at the back of the calf, just above the heel.