Not much is known about Bianca's past. She and Nico were born before World War II, so Hades never broke the oath he took after the war to never have any half-blood children again.
Bianca and Nico both lived in Washington, D.C. at some point. When Bianca and Nico were very little, their mother,Maria di Angelo, died when Zeus struck the hotel they were staying in with lightning while trying to kill Nico and Bianca. The Oracle of Delphi, showing up shortly after the destruction of the hotel, was cursed by Hades to never have her soul rest, and to stay in her body until it rots (and longer). He cursed her because she kept telling him that he should have given Bianca and Nico to Zeus as she knew their future.
Shortly afterward, both were brought to the Lotus Hotel by the FuryAlecto who was disguised as a lawyer. Hades had to erase their memories in the river Lethe, so they wouldn't remember anything about their previous life.
After what felt like a month in the Lotus Hotel, which was actually about 70 years, they were taken out by the same Fury (Alecto). Hades wanted them because he wanted one of them to be the child in the prophecy.
Bianca is first introduced in The Titan's Curse, as a half-blood of unknown parentage (but it was realized after they figured out Nico's parent). After being rescued from the manticore by Percy Jackson and Artemis, Bianca makes the decision to become a Hunter. She shows signs during the quest of being a child of Hades when she is able to slay some of the skeletal warriors easily when the others were unable to.
Bianca later joins the quest, but she dies halfway through the adventure. She stops to pick up a Mythomagic figurine of Hades, which, according to her, is the only one that Nico doesn't possess. However, as the other quest members have warned, removing an item from the Junkyard of the Gods causes a malfunctioning Talos robot to attack them. Bianca goes inside the machine to stop it , but in the process crashes the robot into some power lines. Percy, Grover, Thalia and Zoe search for her from when the incident happened until dawn, but they never found her. Nico learns of her death at the end of the book. He believes that Percy has let her die despite promising not to let Bianca be harmed. Nico flees, and Percy discovers in the process that the di Angelo's are children of Hades.
Percy finds out that Bianca was sending him Iris-messages so he could see what Nico and the Ghost King Minoswere up to.
Later in the book, Bianca comes back as a ghost, through a ritual by Nico. She explains to Nico that her death wasn't Percy's fault and there was nothing he could have done to help, as she made the fatal decision herself. She also tells him he must forgive Percy, as holding grudges is the fatal flaw of a Hades child. This allows her brother to make amends with Percy and ensure he is on the gods' side for the war.
In The Last Olympian, she appears to her brother when he tries to summon their mother's spirit. She warns Niconot to summon her; explaining that she is the one ghost he is not allowed to summon and that she has been hidden by Hades due his grief over her death. Instead of summoning her Nico sees a memory from his early childhood where Maria was killed by Zeus in attempt to get to the children.
Bianca is quiet and shy, and loves her brother, but dislikes caring for him all the time, and was relieved to be able to be her own person when she joined the Hunters of Artemis. She got along well with Percy, but he was angry with her when she joined the Hunters instead of coming to Camp Half-Blood, as this made him feel as if losing Annabeth had been for no reason at all and that she was also being selfish with Nico. He later forgives her, as she told him she joined the Hunters so she could live her own life and that she felt Camp Half Blood would be safe for Nico for she believes that there are a lot of people like Percy there.
Her father, Hades, mentioned that Bianca would have made a better child of the prophecy than Nico.
Like her father, both Bianca and Nico have a habit of gesturing with their hands while talking and when they are on edge.
Bianca has black eyes that are like her father's, which gleam with either madness or genius, and silky black hair. She is lean and about average height. She has olive skin, and wears a floppy green hat that hides her face. She gains the silvery aura all Hunters have after she pledges herself to Artemis, and doesn't hide behind her cap anymore. She pulls her hair back into a braid like the other huntresses, with golden strands that glow.
Bianca doesn't show many demigod powers throughout the series, but she can probably summon the dead like Nico is able to. However, in The Titan's Curse, she managed to kill one of the Skeleton Warriors by stabbing it, causing it to burst into flames. This is most likely due to her parentage, being a daughter of Hades.
Bianca di Angelo's fatal flaw may also (like her full-blooded brother Nico) be holding grudges. After her death, Bianca says that holding grudges is the demigod children of Hades' fatal flaw. In the fifth book, Nico tells his father that he (Hades), is holding a grudge that could end up killing the Olympians and the campers. It may also be a strong bond with those she loves (Nico). This may be because she was killed because she picked up a metal figurine of Hades, the only Mythomagic figure Nico didn't have, an act of misplaced sibling love. She dies by destroying a prototype of Talos, the metal giant in the Junkyard of the Gods.