I enjoy the mythos around Charon. If you lived your life to the point where you didn’t have a single person to care for you enough to make a small payment in your name (think 2 pennies), you suffer the fate of merely waiting. He’s like a minimalist renown filter of sorts. It’s like a judge of character, so to speak, based on what others would do for you when you can’t act.
Cerberus was next in line to the house of Hades, but Charon was not his master. Hades was.