Prometheus was a Titan known for creating humans and gifting them with fire against Zeus's wishes. As punishment, Zeus had Prometheus chained to a rock where an eagle would eat his regenerating liver daily. After thousands of years, Zeus agreed to free Prometheus if he revealed a secret - that Thetis would bear a son greater than his father. Zeus used this information to prevent such a threat, and sent Hercules to free Prometheus from his torment.