|“||Certamente. We will stay together. Zeus is un imbecile.||”|
While searching for Ethan Nakamura in the Underworld, Melinoe, the goddess of ghosts appears before Percy Jackson, Thalia Grace, and Nico di Angelo to torment them with visions of people they had lost. While she appeared to Thalia as her mother, she showed herself to Nico as Maria di Angelo.
When trying to summon Maria, Nico instead finds out much information about his mother through the ghost of his sister Bianca.
During the time she and Hades were together, the Great Prophecy had been spoken, and World War II was beginning, with some of his other demigod children involved, on the side of the Axis Powers. Hades wanted to hide Maria and the children in the Underworld, so that Zeus would not be able to find out about them. However, Maria refused to raise her children there.
While she was in a hotel, Zeus destroyed it, killing Maria. Hades was only quick enough to shield Bianca and Nico. Hades had wished to revive her in his loss, but Alecto, the Fury, reminded him that as an immortal, he had to respect the forces of life and death. A devastated Hades then told Alecto to bring Nico and Bianca to the Lotus Hotel and Casino where time stands still.
It is evident that Hades had loved Maria dearly: gods rarely revealed their true nature to a mortal, even if it was one he or she loved and had children with. However, Hades not only did so with Maria, but also fathered two children through her (unlike having twins), and continued to see her until Bianca and Nico were about 5 and 3-years-old respectively. He was even prepared to disregard Persephone (his own wife)'s feelings by promising to build Maria and their children a palace of gold to live in if she would agree to go to the Underworld with him.
Maria was also revealed to be one of those rare few who saw beyond the dark and fearsome persona that Hades always put up, and commented that other gods might neither fear him nor view him as an outcast if they were able to see him as she did.
Her tragic death caused Hades a lot of devastation and pain, as well as bitterness towards his family, which in turn, lead him to the curse the Oracle. Nico was able to partially use the memory of his mother to convince Hades to fight with the others, telling him she was right about families sticking together and that Hades should prove himself to be more than what his siblings thought of him.
Maria was described by Percy to be a very beautiful woman whom both of her children resemble.
In The Sword of Hades, Percy describes her as a woman in an old-fashioned black velvet dress with a matching hat. She wore a string of pearls and white gloves, and her dark hair was tied back.
In The Last Olympian, Maria was described as having Bianca's smile and Nico's dark brown eyes and wore a black dress, gloves, and a black veiled hat like a star from an old 1940s movie.
- Maria was one of the few who always saw Hades' kind and generous side, and even speculated that if the other Olympians saw it as well, they would not spurn and fear him nearly as much.
- Maria di Angelo and Marie Levesque, the mother of Hazel Levesque, have a lot in common:
- Both were both at one point lovers of Hades/Pluto.
- Maria and Marie were both killed by an immortal.
- Their daughters were both killed.
- Their daughter's time was reserved and then brought back to life or for example, Bianca being stuck in the Lotus Hotel and Casino and hadn't even noticed seventy years passed by.
- Their first names are similar.
- Both women have a connection with the Mist (Marie's ability to manipulate it and Maria's ability to see through it).
- Di Angelo means "From the angel."