Bianca/Nico Head cannon.

Nico saw her in his dreams, his Sister running from a tall robotic giant, Nico tried to scream as Bianca ducked behind a pile of scrap next to Percy. Percy talked to Bianca quickly and Nico didn't hear what was said, but he saw Bianca run, run towards the Giant as it raised his foot and she climbed inside.

Nico screamed and tried to run towards her, to touch her, but he was rooted to the spot, Suddenly his scenery changed and he was inside the robot with Bianca, Electricity sparking about the hot room she was in and Bianca was thrown and hurled about as the Robot moved, She was thrown against the wall and let out a soundless scream as she was electrocuted again, she panted and hit another button, determined to end this robot, even if it was the last thing she would ever do.

Nico looked on in horror as he watched her, screaming and shouting her name til he was hoarse, tears streaming down his 10 year old face. Bianca took a deep breath, her lungs rattling as she looked directly at him, or through him. "I'm sorry Nico." She panted out, obviously fighting to stay conscious. "I'm sorry I failed you."

And with that the room lit with electricity sparking and shaking her body until she slumped against the wall.

Nico collapsed to his knees, screaming his sister's name, trying to touch her, before some invisible force like a bungee cord pulled him back, and a figure appeared by her side, touching her face. "Bianca di Angelo." It said as he picked up her limp body. "A trial for the Daughter of Hades."

Nico awoke in a cold sweat, panting with tears streaming down his small face; he quickly got to his feet and exited the cabin, walking towards Percy's. 'Percy wouldn't do that to her, right?' He thought, frowning at the ground. "He made a promise to protect her, he wouldn't let her die. It's just a bad dream..." He mutters to himself, unaware that no more than 100 steps behind him, a certain figure stood her green hat in her hands. "I'm sorry Nico"

AN: -I'm sorry for all these feels. Also. Sorry it was short. It was just a head cannon