Nico's P.O.V.

I hold Bianca's hand, peering through the crowd and standing on my tip-toes. I'm only eight.

"Too short?" she teases. I huff.

"Just you wait, I'll be as tall as you in two years."

Her eyes twinkle, and I realize how much I've missed her. She looks exactly like how she did before her death--warm brown eyes, dark hair, and a playful expression. Her hair is tucked under her usual green cap. I used to idolize her, and then she had to die. It was all Percy's fault, and the stupid gods. I forgave them, but my heart was still broken.

I'd always longed to be a big brother instead of a younger one--but I hadn't expected it so happen in this way. For my sister to die, and be replaced by Hazel. I took on the role of big brother, but it didn't seem right.

My eight year old self jumps up and down with excitement. "Where's mother? I want to check out the festival!"

She rolls her eyes. "You just want the food."

"You can't blame me, sorella," I respond. We walk along, holding hands and sightseeing. The road is cobbled, and a cook shouts in Italian at another man as a column of fire shoots up his face. Bianca stifles a giggle. "He just singed off his eyebrows."

"I told you cooking was dangerous."

My heart almost stops. This isn't a memory. It's just a sim. This never happened.

I stare into the warm honey brown eyes that don't exist. "This isn't real. You're not real."

Bianca's brow furrows. "Of course I'm real, Neeks. What do you mean?"

A cold feeling settles over me. "You're dead. You're gone. You're not coming back."

And that's my fear. I'm afraid of the fear landscape itself. I don't want it to show me scenarios that will break my heart.

Bianca brushes my hair out of my eyes. "Nico di Angelo, stay strong. You're the strongest boy I know. And never give up hope. No matter what happens, stay strong and hold on to hope. Promise me."

"I-I promise." It may be fake, but they've captured her essence perfectly. The real Bianca would say this.

Bianca's form becomes transparent and ghostly. She slowly fades into the background. Soon she vanishes completely, and her words are whispered back to me: Stay strong and hold on to hope.

The image swirls into a blur of color, and then I'm somewhere devastatingly familiar.

I'm underground, beneath Rome. I want to kill whoever created simulations.

I feel extremely weak, and I breathe in short bursts. I walk with a slight limp.

Annabeth is being dragged into the pit, her ankle wrapped in spider silk. I knew that Arachne's weight was pulling her in. The pit radiates fear and death, and beings so ancient that the gods are only children compared to them dwell inside. Tartarus.

Annabeth is yanked backward, and Percy lunges. He grabs her arm, but the momentum carries him along with her.

"Help them!" Hazel screams, struggling to disentangle her cavalry sword from the rope ladder. Hazel's cry is drowned out by the chaotic jumble of voices and the rumbling of the cavern. Cracks spiderweb along the floor, and I back away quickly.

The daughter of Athena is at the edge of the pit, legs dangling off the side. Percy is her only anchor, the only thing keeping her from plummeting. She sobs and tightens her grip on his arm.

"No," I hear Percy mumble, realization hitting him like a tidal wave. "My sword..."

But Riptide is well out of his reach. The only way for him to get it would be to release Annabeth. And he wouldn't do that for a million drachmas.

Annabeth slips over the edge, Percy in tow. Hazel and I rush to the edge.

Thank the gods. Percy managed to grab a ledge about fifteen feet above the endless black void below them, and he grips her wrist tightly, both of them covered in nicks and scratches and dirt and blood.

No escape, a buzzing voice says from the darkness. I go to Tartarus, and you will come too. 

Arachne. I curse under my breath.

The pit shakes, and Hazel and I inhale sharply. Her friends are still trying to get the Athena Parthenos on the Argo II.

I thrust out my hand in desperation, but they're too far away. Hazel yells louder, but it's no use.

Some deaths cannot be prevented. Hades' favorite motto.

Prevent this one, I plead in my mind. Not Percy. Anyone but him.

"Percy, let me go," I hear Annabeth croak. "You can't pull me up."

The effort of hanging on to the ledge, bearing Annabeth's and Arachne's weight, and the gravitational pull of the pit was too much for the son of Poseidon. His face is almost as pale as mine.

"Never." Percy raises his head and stares at me. "The other side, Nico! We'll see you there. Understand?"

My eyes widen. "But--"

"Lead them there!" Percy shouts. "Promise me!"

His sea green eyes bore into my dark brown ones, and my heart feels crushed. 

"I-I will." What had I just promised?

From the void, Arachne's sweet and saccharine voice can be heard. Sacrifices. Beautiful sacrifices to wake the goddess.

I scream along with Hazel, desperation rolling off me in waves. The pit shakes again, and debris break from the walls and fall into the void.

Percy lets go of his tiny ledge, and the son of Poseidon and the daughter of Athena disappear through the void.

I fall to my knees and grit my teeth. I only watched while my hero fell into Tartarus with Annabeth. I was powerless to do anything.

Hazel wraps me in her arms, consoling. Even though I should be comforting her.

"We have to believe in them, Nico," she says, her voice quivering. "They'll survive."

I nod wordlessly. It takes me a long time to calm my erratic heartbeat.

__________.__________

I sit upright in a white chair, and Four stares at me with narrowed eyes.

"You're Italian?"

I slap my hand on my forehead. "Seriously? That's all you got from that?"

He almost smiles. "Your sister, Bianca. Percy and his girlfriend falling into...Tartarus."

I frown. "How did you know?"

He shuts down the computer. "A certain son of Poseidon shared his adventures with me."

I silently curse Percy for being an idiot. "You weren't supposed to know."

"We're about to have a war. I think everyone has a right to know. You demigods could be useful allies," Four says.

I raise an eyebrow. "You aren't as clueless as I perceived you to be."

"Dauntless aren't all dumb. Some of us are intelligent when we want to be."

"So you know we're outsiders. Spies," I say.

"Yes. Tell your other friends that I'm with you. I hate the faction system as much as...Evelyn."

"Evelyn Johnson. You should just accept the fact that she's your mother, Tobias."

His eyes harden. He cocks a gun and aims it at my head. "My name is Four. And she isn't my mother. If you want to live, you'll call me Four."

I stare him down, which is disconcerting, as he's a foot taller than me. Something tugs at my gut, and the ground rumbles at my will. The shadows grow larger and darker.

"Don't anger a son of Hades," I say. "It isn't good for your health."

He puts the gun back in his holster, his eyes never leaving me. "Can I trust you?"

"I'm sure I shouldn't trust you, but it looks like we'll have to trust each other. You won't win your war without us."

We shake hands. "Thanks for joining our side, Nico," Four replies.