AN: Another random idea I wanted to share with the fandom. Enjoy and thanks for reading~

Chapter 1

"Otis trudged over to the dais, stopping occasionally to do a plié. He knocked over the jar, the lid popped off, and Nico di Angelo spilled out. The sight of his deathly pale face and too-skinny frame made Percy's heart stop. Percy couldn't tell whether he was alive or dead. He wanted to rush over and check, but Ephialtes stood in his way." – Mark of Athena ~pg. 429

Despite Piper's best effort, the battle between the giants and the trio of demigods broke out too soon for her to get Nico to safety. She had only been halfway to his still form when she'd been surrounded by hungry leopards. There was barely enough time to will a variety of meat at the large wild cats via her cornucopia so they wouldn't tear her limb from limb when a sandbag caught her shoulder and sent her crashing to the ground.

Several feet away the fight was picking up. Jason and Percy landed blows on the twins that would have sent them crumbling to dust if they'd had the help of a god; however, Bacchus chose to appear only after the situation started to seem bleak. It was then the Roman god of wine transported Piper to safety while sitting back to watch the two sons of the Big Three take on his old enemies. After Bacchus killed the giants, which took forever to the now exhausted Percy and Jason, Leo and the rest of their friends arrived on the Argo II. It was when Leo, Hazel, Frank, and Coach Hedge made their way off the ship to stand in front of the trio that Piper suddenly gasped.

"Guys," she said worriedly as she gazed in the direction Hazel's newly rescued brother was still lying on the ground, "Nico hasn't moved yet. He's still unconscious."

"What?" Hazel shouted. She turned her attention to where the bronze jar had been knocked over earlier. When her golden eyes locked on her brother's form she took off sprinting, her lips locked in a tight frown. The rest of the party followed seconds later.

As Hazel knelt next to the motionless son of Hades, Percy swallowed back a bout of guilt. He'd originally planned on wailing on the kid for not telling either camp about the other's existence. Looking at him now though, Percy knew he wouldn't be doing anything of the sort.

Nico di Angelo had always been pretty scrawny. He'd also been getting paler and paler for some time, as he was probably spending more time in the Underworld than the he was aboveground, but now his appearance was that of a freed war prisoner. His clothes were in tatters and through the thin material the demigods and satyr could count every one of his ribs. The dark circles under his eyes were just as prominent as the multiple untreated wounds covering his body. Even after they got him to safety Percy wondered if he would ever recover from what he'd been through. Being captured by giants and stuck in a jar for a week slowly dying could be traumatizing.

"No," Hazel suddenly whispered, the tears escaping her beginning to cascade down her cheeks.

Frank immediately went to her side. "Hazel, um, I know he looks bad, but he'll pull through. We should get him to the Argo II while he's out so—"

"Wait," Jason suddenly interrupted him. Deep down most of those there knew the strong daughter of Pluto wouldn't be crying as hard as she was unless… "He's not unconscious, is he, Hazel?"

A line from Ella's prophecy seemed to echo through their heads.

The twins snuff out the angel's breath, who holds the keys to endless death.

Snuff out. Did the line really mean what it was saying?

She shook her head roughly, an arm coming up to wipe some of the tears off of her face. "H-he's—Nico is…"

"Dead?"

Everyone gathered around the body of their friend screamed, eyes rising to see the ghostly form of… their friend?

Nico sighed tiredly, his appearance looking much different from the dead boy on the ground. Other than the fact that he was partially transparent, he could almost pass as a human. He was wearing a clean, undamaged version of his usual attire consisting of black jeans, worn sneakers, a skull T-shirt, and an oversized aviator jacket. His skull ring adorned his finger just as it always had too, but that was where the similarities stopped. For the first time since Bianca the son of Hades appeared to be healthy. He had a lean amount of muscle and a healthy amount of fat over his ribs, his skin was almost back to the olive tint it had been around four years ago, and he looked more alive than ever.

Funny. He looked more alive now than he did when he was dead.

"Oh, Nico!" Hazel threw herself at him, landing in his arms despite him being a ghost. She buried her face in his shoulder and cried; Nico held her quietly and closed his eyes for a full minute until gently pushing her away. When he spoke a moment later his voice was soft.

"It's okay, Hazel. I'm the Ghost King, so dying wasn't as terrifying as it could have been. Father made the journey as smooth and painless as possible," he explained. Gratitude shown in his dark brown eyes at the memory. "Right now with a war on the horizon he is allowing me to ignore going to the Underworld in favor for assisting you and everyone else on the quest."

He then turned to the rest of them with a nervous smile tugging the corner of his lips up. It startled the demigods, especially those who had met Nico before, that he would smile after everything he'd been through. He rarely smiled as it was.

Just as he was about to speak though, Percy stepped forward and pulled his cousin into an embrace.

"I'm so sorry we didn't make it in time," he confessed with tears in his eyes. The part of Percy that strived to protect his friends and loved ones was devastated. "I failed you again, Nico. I understand if you hate me."

Nico hurriedly broke the hug by pushing the son of Poseidon away, a hint of color rushing to his cheeks as he glanced at those around him sheepishly.

"Percy, I never truly hated you. I only realized that after the initial shock of what you told me. When Bianca told me it was her choice and not to blame you I already knew deep down I could never hate you for failing to keep your promise. She made her choice, and long ago I made my choice to forgive you. And I know you don't think I'm trustworthy, but—"

"I do trust you," Percy declared with an air of finality. "That incident with your father was understandable. I realize that now. He tricked you, plus he almost incinerated you for going against him. Besides, without your help in the labyrinth, with Luke's mom, Hestia, the whole bathing in the Styx, not to mention bringing an entire army of the undead and your father to help us win the Second Titan War, and protecting my mom and Paul during the war I would probably be dead. Despite how unfairly I treated you and how much you did for me I let one mistake blind me from being your friend. I just wished I had realized all of that before…"

He didn't have to finish his statement for everyone to know what he meant.

For a long moment Nico simply stared at Percy. It was several seconds later when a pained look shown in his eyes before disappearing.

"Thank you," he said finally.

"You don't need to thank me. I should be thanking you."

Rolling his eyes, Nico opened his mouth to speak when suddenly the floor began to shake.

"Um, sorry to interrupt," Leo raised his hand as if he were in school and desperately trying to get called on. "Now that the floor is caving in it would be a great time to head back to the ship. Also, Gaea sent a vision of Annabeth. She might be hurt, so we should hurry. Nico can tell us where the Doors of Death are on the way."

Percy's eyes widened worriedly. "Annabeth is hurt?"

"Wait!" Coach Hedge yelled. "What do we do about…?" He gestured at the body on the floor, and the demigods turned to Nico. It was his after all.

"Leave it," Nico instructed. Without any traces of emotion on his face he slipped the skull ring off his body's finger and placed it in Hazel's open palm. She slipped it onto her own finger with a sniffle. "There's no use bringing a dead body on the ship, but once we're out of here I'd appreciate making sure this place goes down. I don't want it just, um, left out in the open," he finished in a mumble.

Hazel seemed as if she wanted to argue, but the resolute look on her brother's face stopped her. With heavy hearts the demigods, satyr, and ghost made their way back to the ship. Once they were safely inside and up in the air, Coach Hedge fired at the building one last time. Within seconds the crumbling sped up until only a mess of metal and concrete was left. Hazel held Nico's hand as he stared down at the scene.

No one mentioned the single tear that escaped the son of Hades.

As Percy went to tell Leo about what Bacchus said about the Emmanuel Building's back parking lot he couldn't help but be reminded of Bianca di Angelo, whose body had been buried under a pile of metal and junk just a few years ago.

The Fates must have a thing for dark irony.

A couple of minutes later, with help from Percy and Frank, the Argo II set a straight course for where Annabeth was. In the meantime everyone convened at the helm to hear about each other's encounters. Once Leo told everyone about what happened concerning the Archimedes spheres and Jason relayed how the fight with the twin giants had gone down it was Nico's turn.

Nico's ghostly form sat perched on the railing. It became apparent that while he could physically touch people and objects like the sword at his side, which had been returned by Hazel, he was practically weightless on top of being partially see-through. He admitted to being able to go intangible when he so desired, but he usually tried to remain somewhat solid.

"Firstly," Nico started while gazing at them evenly, "I want you to know that I did know about both camps. My father led me to Camp Jupiter and told me to keep each other's existence a secret because neither side was ready yet. Chiron suspected I knew, since he was keeping the same secret, but the gods would've had our heads for starting a civil battle between demigods. As much as I wanted to tell you when you arrived, Percy, I couldn't."

The son of Poseidon nodded, and beside him Jason felt guilty for calling him shady for simply doing what he needed to do.

"Why did he pick you to harbor such a secret?" Piper asked with a frown. "That seems like a lot of responsibility."

"It was because of Hazel, right? She's a daughter of Pluto and needed somewhere safe to live after rescuing her from the Underworld." Frank guessed.

Nico shook his head. "That's what I thought at first too, but it turned out I needed to realize how important it was that I search for the Doors of Death in order to assist you all on your quest. Finding them became my top priority."

"There are two sides to the Doors of Death," he stated. "Once side is in Greece, and the other is in…"

Leo tilted his head confused when the son of Hades' didn't continue after a few seconds.

"Is in where?" Piper prompted lightly.

A troubled look crossed Nico's face at the question. From where Frank stood barely a foot away from the Ghost King, the son of Mars noticed his lithe form trembling. It became even more apparent something was wrong when his form began to dissolve. Well, not dissolve really, but the edges of his body were becoming smoky.

"Nico!" Hazel went to grab his hand, but hers passed right through.

"S-sorry," Nico replied shakily. "I know ghosts sometime become more unstable when certain topics that either relates to their death, dying wishes, or someone that wronged them while alive comes up." He took a deep breath, but while his trembling had ceased his form was still wispy. "The other side of the Doors of Death is in the Underworld. More precisely, it is in T—"

He slapped a hand over his mouth and turned his head away. It was too terrible so say.

After a moment, Percy caught on with a gasp.

"Tartarus."

Nico looked at him with glassy eyes as his body blurred even farther.

"I thought there was no place in the Underworld I couldn't go." He closed his eyes tightly, hands clasped together despite being mostly wisps. "I was such a fool. I got too close, and Gaea dragged me into the pit. Nine days," he said in a choked whisper. "It took nine days to fall, just like the historians guessed. Her forces overwhelmed me almost as soon as I escaped the River Cocytus."

"You don't have to tell us anything else," Hazel said gently. "You've told us what we needed to know. If you don't want to talk about it we understand."

He shook his head, opening his eyes to reveal barely concealed terror. It was as if he hadn't heard her.

"I ran into Akhlys, the goddess of misery. She told me she couldn't make me more miserable than I already was. Monster after monster came after that. I fought for all long as I could, but more just kept coming. When both giants appeared I knew it was over. T-Tartarus itself was there, mocking me and everyone I care about. I almost went insane," he murmured so quietly they almost didn't catch it. His arms curled around himself out of fear. "Then the giants put me in the jar. After taking a few of the seeds from Persephone's garden, as the days went by, I'd lost home that you would come. It almost made me happy, since I knew it was a trap. I didn't want anything happening to you because of me."

"We need to close the Doors of Death so we can defeat Gaea," Jason intervened, "which meant we needed to rescue you since the quest Ella gave us said you had 'the key to endless death'. But, Nico, we would have come anyway. Hazel wouldn't have had it any other way."

The fear ebbed from the son of Hades at that statement, his gaze meeting his sister's with affection Jason hadn't thought possible of him. Guilt rushed the son of Jupiter. He made a mental note to not to judge others without getting to know them first.

"I have a question."

Everyone turned to Frank, who quickly squirmed under all of the attention.

"Do we need to close both sides of the Doors of Death in order to stop Gaea's forces from reaching the surface and helping the bad guys? We can't just close the ones in Greece?"

Nico frowned. "No, unfortunately. The doors would have to be controlled on both sides in order for them to be closed. With everyone fighting together at the House of Hades we may be able to cut the chains there, but unless you had a team fighting on the Tartarus side at the same time the monsters will keep coming."

"The House of Hades?" Leo whistled. "Compared to the Doors of Death that sounds just as fun as a haunted house."

"I can guide you through my father's temple. Together we should be able to gain control of the doors there, but I don't have any clue on how to close the other ones."

"Maybe it seems like the stupidest idea ever, but maybe some of us could go to Tartarus?" Percy offered weakly. "If we could find a god or two that knows how important it is that we close the Doors of Death, then perhaps—"

Nico cut him off, his voice final as he hopped down from the railing of the ship and stood so he was directly in front of Percy.

"No. Thanatos, even Hades wouldn't go there. Gaea's monsters are too strong in their home court. Tartarus itself is a living being; everything is designed to hurt, to torture, to kill demigods like us. Everything there will try to break you," as he said this he began shaking once more. Out of fear or anger no one could quite tell. "They take your worst fears, your desires, and those you care about and use it to squeeze every ounce of sanity and hope from you. Don't ever say you would be willing to enter that place, Percy. Please."

The plea was so desperate Percy knew he would tell the kid what he wanted to hear. Before he could, however, the Emmanuel Building came into view.