Tartarus.
The trinity of demigods laid sprawled on a craggy rock that jutted out far into an infinite abyss that surrounded them. The portal they had come through had closed, plunging them into almost complete darkness. A nimbus of light flowed off Chaos as she stood at the beginning of the craggy rock, blocking any way of escape. Darkness swirled below the large jutting stone, making any single misstep their last.

Death.

The feeling was everywhere. While they knew they were in the Underworld, this section of Tartarus was unlike the one that existed in the gloomy chasm. This abyss was different: dark, primordial, and absolutely malicious.

Evil.

The sense of it buzzed around them and was almost tangible, sending chills that had nothing to do with the cold that also encompassed them running down their spines. The malevolent force was flowing towards them from all directions, horror lacing through it. The three half-bloods knew that the very darkness that surrounded them was Tartarus, the ancient god that stood for everything evil and murderous . . .

And Chaos was planning to awaken it from its deep sleep.

"The end has come, godlings," the goddess hissed, her voice terrifying and absolutely lethal. "And you are to bring about my rise to power."

"I will die before I assist you," Matt spat, fury raging through him. His aura briefly cracked around him, filling the chasm with a moment of cerulean light. Isabella had revived, and now leaned on Thalia for support. All three of them were still sitting on the craggy rock, too exhausted to move.

"That is exactly what you will do, Son of Odin," she said, her voice sounding almost reptilian, her tone almost joyful. "You see, half-blood, in order to awaken my lover, Tartarus, the blood of the three most powerful demigods ever to walk the earth must be spilled and given to him. Those three would be you."

Their mouths dropped open in unison. Unable to hide the shock in their faces, they stammered and attempted to form words but to no avail. It felt as if their whole world had gone numb and they were slowly spiraling into the abyss, being pulled in by some unseen force.

"You three are powerful beyond belief – the children of the three most commanding gods – and that power I shall take and channel to give new life to Tartarus, and then I will release him upon your earth and watch as it burns." Chaos cackled as images of the dying and scorching world surfaced within the minds of Thalia, Isabella, and Matt. "And," she continued, "no one – not even Hope – will be able to stop me!"

"We will stop you," Thalia growled. "We will not rest until you are dead."

The primordial goddess grinned, and the sight was terrifying. "My dear Thalia, you will be dead before you ever get the chance to stand in my way." To keep her threat, Chaos lifted her jet black hand, her palm facing towards the daughter of Zeus.

The choking came first.

Thalia clutched at her throat, feeling her windpipe slowly close up. Her brain began to throb, the sound of blood pumping clearly audible in her ears, the iron tang of the crimson liquid filling her mouth. Her nose began to burn with the smell of something dark and ancient, not that she could get a firm grasp over the odor through the gasping and choking as she attempted to breathe. The darkness around her faded and a stark, white light filled her vision; the menacing acts being thrust upon her disappearing.

Then, suddenly, she was yanked back into the world, gasping for deep gulps of air as the aftermath of Chaos incantation began to wear off. Thalia squeezed her eyes shut, un-wanting to see what had occurred.

Matt stood behind the primordial goddess, an iron dagger protruding from her abdomen, stuck through her from her back. Chaos slowly looked down at the gray tip, black mist curling from the wound.

Isabella watched as she slowly began to lose form, unable to hold together her shape whilst the dagger penetrated her core, its strange and unique energy coursing through her veins, killing her. Silver tears began to slowly drip from here same metallic shade.

Something was happening to the primordial goddess, something . . . something . . . something . . .

Matt quickly pulled the dagger from her back, the blade tipped with what looked like black blood. Chaos shifted and shuddered one last time, before exploding into a cloud of ash, swirling around them before spiraling down towards the depths of Tartarus, a sharp wind beginning to whip around them.

"How did you know . . .?" Isabella said, slowly, bringing Thalia to her feet.

Matt looked at the dagger once more before throwing it into the dark chasm. "Back in New York, we all saw the effect her magic had on us, but it was easily broken. Her incantations were weak and feeble, and there was no reason for such to happen to the most ancient thing in the universe. I remembered that in many mythologies, the gods had to flee the World of Man because of the invention of iron and how even being near it could kill them. I realized how much iron was in New York, making her spells hard to keep durable, and so . . . well, I actually went out on a limb. If that wouldn't have worked, I don't . . ." His voice trailed off as he realized that Isabella and Thalia were no longer looking at him, but over his shoulder, beyond him. Matt slowly turned around, drawing in a sharp gasp of shock at the sight of . . .

Annabeth.

She stood at the back of the huge, opening-less cave, a portal of blinding white light behind her. Her hair twisted and shifted as if underwater, the golden strands shining. Her eyes had changed to different colors – one silver, one gold – and her clothes had changed to an ancient Greek dress, white and beautiful.

Energy and power no longer radiated from the daughter of Athena, although they could all feel the change within her. Hope had become less dominant, but still resting within her, lending her its powers. But Annabeth was herself again: her soul had broken free from its cage and had restored control . . . but not before turning back Nidhogg and Amehait, relinquishing them back to their dark and torturous realms of containment.

"Annabeth!" Thalia screamed gleefully, but her words were drowned out, swallowed by the raging maelstrom that now suddenly swirled around them.

Matt realized darkly that the typhoon that now released its fury around them was the essence of Chaos. He suddenly remembered a legend – one long lost and easily overlooked legend – of the primordial goddess being caged by the gods in the flesh and bones of a body, unable to release her pure, raw energy that had created the unending world and its neighboring realms.

And he had loosed her.

She had planned it all: the conclave, Delphyne, Mnemosyne and the Muses, the Battle for New York, even the gift of Pandora's Box. Chaos had known – and planned – everything they had done, making sure it had all gone according to plan. He doubted if any of her tools used to help himself, Thalia, Isabella, Annabeth, and even Percy to where they were knew that they had been chess-pieces, maneuvered expertly by the hand of Chaos. She had even schemed to have them at that moment so she could release Tartarus and even herself from her bonds, the iron nullifying the gods' incantation that had been cast to cage her. And he realized – too late – what she was about to do.

"Annabeth!" He screamed over the storming gale that burst around them, threatening to shake them from their precarious perch on the dark, jutting stone they crouched on. "Run! Get out of here now!" She looked at him puzzled, energy endowed to her by the pure essence of Hope pooling in her hands, glowing, but she did not move, not understanding the danger she was suddenly in. Without the primal being of Hope within her, controlling her like it had done at the Battle for New York, she was open to almost any source of raw energy. She was like a drug to the immortals, a drug they used to get there fix, to gain power and prominent dominance in the World of Man. And, in Chaos' case, to gain a personified form with which she could aim her dark energy out across the earth, reclaiming it as her own . . .

The storm around them spun faster, flashes of lightning now cracking within it, low thundering echoing through the abyss that was Tartarus. It could've been her imagination, but Isabella could've sworn that the darkness below had grown closer and was laughing madly – and triumphantly – at them. Tartarus was so near to being awakened from his punishment that even the thought of it terrified her more than the winds that swirled around them. Strange faces and expressions would appear in the gale, twisting and shifting into gruesome and exotic looks of horror and triumph combined that they immediately recognized as the masks of the primordial goddess.

Annabeth realized far too late what Chaos was planning, and she wasn't prepared enough to fight the goddess, making herself a defenseless rowboat in the heart of a storm, a tsunami looming before her, about to crush her, about to consume her . . .

And then, the typhoon of wind turned into black clouds streaked with glowing specks that became spears of light as they were thrown around at light-speed. Chaos – in her energy form – swirled around Annabeth, creating a dark cocoon of sable mist and smoke around her, taking the air away from her lungs, weakening her. The energy spun faster and faster around her, becoming a part of her . . .

Matt, Thalia, and Isabella watched in horror as their dear friend was warped by Chaos, and they were powerless to stop the transaction. Isabella and Matt and combined their magical powers – fueled by Thalia's energy – and had attempted to reach Annabeth, but with little avail. They could do nothing but watch in terror and foreboding, knowing that when the black smoke faded, the Annabeth they would see would not be Annabeth they knew.

Then the clouds cleared, revealing the figure of the daughter of Athena . . . just before the black smoke twisted and forced itself down her throat through her mouth, entering her soul. Chaos had possessed Annabeth Chase, and now the only thing that could've stopped her – Hope – she was in possession of, including the body of the only person who could hold the primal power.

Chaos was now – ultimately and infinitely – invincible.