In the Rape of Persephone Hades, after being given permission by the king of the gods, kidnaps Persephone, his niece. He steals her from the fields where she's picking flowers with her friends. Hades takes her on his black chariot down into the underworld where he tells her she will rule as his queen. She's angry and afraid and horrified because she's heard stories about how terrible her uncle is from Demeter and the other gods. He rules over darkness and death. But she comes to learn that death is his dominion not his nature. He is kind and reserved. He brings her gifts daily. He never pressures her and he is never cruel. He gives her anything she asks for, except freedom, and eventually she falls in love with him because of his kindness. By the time Persephone eats the seeds from the pomegranate she is happy to stay and she is sad when she finds out she has to leave her husband.
It's our interpretation of death and the underworld that makes it something scary and horrific. There are several layers to Hades (the place and the god) both good and bad and in between (like with both god and man alike). It's unfair for us to think that, because he presides over Hades that he is automatically evil. He rules Hades because that's the realm that was left when he and his brothers chose their domains. But he is the only one capable of ruling it. Persephone sees Hades' power and understands that he has an important job in the world. Without Hades we would be lost. Our souls would have no place to go once we died (something we didn't even do until Zeus took over).
Hades' Roman name is Pluto which means wealth. He is the god of wealth because he rules the Underworld. No matter how much a mortal has, however rich they are, they all go to Hades. Even the gods, once they die, will go to Hades. He is the god of wealth because when the world ends there will be nothing but Hades. We get all of our riches from the Earth which he rules.
Christianity has taken the idea of Hades and turned him into some evil and sinister being and people accept that, but when the Greeks created Hades and when they worshipped him, it wasn't some evil terrifying demon the worshipped, it was a god just like any other.