Hades is the ruler of the dead. He is from the Olympian generation. Hades roman name is known as 'Pluto'. The Greeks would always avoid saying his name out loud in case he was summoned, which they didn't want to do. He was originally known as the "he who must not be named" person if you think about it. He was also known as "the rich one," since he had practically everything. Hades was married to Persephone, who is the daughter of Zeus and Demeter. He did have to kidnap her to marry him, and it caused a huge and terrible famine around the world. Hades couldn't have children though, since he is the god of the dead and couldn't create life, therefore, he has no biological children.
The titans controlled the whole universe which included of the earth, sea, and the underworld, which were chosen by lots, and Hades ended up with the underworld. At first, Hades wasn't happy with his choice until he found out he would get every dead soul and everything included in the underworld.
Hades and Persephone story is not exactly how common relationships work nowadays. As mentioned earlier, Hades did kidnap Persephone to be his queen of the underworld. He was getting lonely being alone with dead souls, and decided the daughter of Demeter ( Persephone ) would be perfect for him. When he took Persephone, Demeter got so upset that she started looking for her. She started looking for her daughter and was so focused she forgot about the crops, causing a huge famine around the whole world. Hades didn't want to return Persephone back to her mother, and he agreed to a compromise with Zeus. The compromise was that Demeter will get Persephone for eight months of the year, and Hades for four. This is also a story used for explaining the changing seasons, when she's with her mother, crops are growing and when she's with Hades, crops die.
Hades did have a dog, named Cerberus. Cerberus is a multi-headed dog, mostly recognized as with three heads, and a serpent for a tail. Cerberus guards the gates of the underworld to prevent anyone, or any souls, from ever escaping or leaving.
A statue of hades and his dog.