Charon is a boatman in river Styx and he is one of the secret bosses in Hades. There is a way to trigger a boss fight, and you will help to beat this boss.
Want to know what is the true ending in Hades? Here's the spoiler-packed answer.
How to Get Titan Blood Easily in Hades & How to use Titan Blood?
Some of the best choices to give Nectar to in Hades are Cerberus, Skelly, and Nyx.