Inheritors of Power Volume 2: The Dragon's Birth, by Caleb Gumbo

As it turns out, being human is far easier than being a god.

Humans have to worry about paying rent, earning salaries, and paying off their student loans, while gods have to deal with homicidal deities trying to kill them.

Kal Knights has reluctantly accepted his new role as the god of death, and Persephone has begun to enjoy her civilian identity as Amanda Evergreen, as well as her position as Kal’s mentor in all things divine. As they settle into their roles, the changes within the underworld become more rampant, and with change brings uncertainty. Some of the changes are favorable to the denizens of the underworld, while others believe the changes only ruin the memory of Hades.

But perhaps the biggest change is the shifting of ancient powers within Tartarus and the birth of the Black Dragon of Death.

This is a sequel. Find the first volume here.