Aqua opened her eyes and found herself drifting in a place choked with darkness. Her feet touched down on a stained glass pillar, one illustrating her on one side and the invader of her heart known as Vanitas on the other. Her muscles clenched as she spun around to face him and the strange, dangerous blade he had in his hand.

"Our union isn't finished yet," he said with a furrowed brow. "The χ-Blade can't stay broken like this." He pointed the broken χ-Blade at her. "Now, you'll join with me, and we'll complete the χ-Blade!"

"Think again," Aqua snapped as she summoned her Keyblade. "I won't let you just worm your way into my heart and take over. I'll remove you by any means necessary and destroy that blade!"
"Is that so?" Vanitas smirked. "The χ-Blade is made of your heart and mine. You destroy it, your heart is doomed. It'll be the end of you!" Aqua's grip on her Keyblade tightened.

"No," she shook her head. "My heart is strengthened by my friends. Terra and Ventus are a part of me, just as I'm a part of them. With my friends in my heart, I will not fall to you!"

"Are you finished?" Vanitas snorted. "Fine. I'll show you just how much good your 'friends' do you!" He leapt into the air and swung the broken χ-Blade toward her, unleashing an x-shaped blast of flame at her.

Meanwhile, Ventus felt sweat beading on his forehead as he rolled to the side, dodging a burst of energy from the χ-Blade held in Aqua's hand. He flinched as Mickey came up behind her and swung his Keyblade at her, and she stumbled slightly before turning around and smacking him away.

"Mickey!" he called as the King hit the ground with a huff. Mickey forced himself back up and gave his friend a quick thumbs-up. Ventus's eyes widened and he barely managed to scramble out of the worst of a burst of flame under him, but the edges of it did lick greedily at him and burned him. His heart pounded and adrenaline slammed through his veins. But his mind started to work out a plan, and he felt like time had slowed down around him. He no longer had to fear allowing his light to grow so bright that it only cast darker shadows on Vanitas. Aqua didn't need darkness right now. She needed light. With her own that he hoped was fighting Vanitas within, he could use his own to aid her.

"I'm coming, Aqua," he breathed as he straightened back up.

"You're just wasting your energy," Vanitas taunted him, and his grip on his Keyblade tightened. He rolled back and blocked another cast of dark magic. He took a deep breath, fighting off the recoil and standing his ground. He focused his energy, opening his heart more than he had ever recalled doing before. And with that, he felt his light flood his body and he took off running toward his opponent. Aqua dove into the ground and he frowned, rolling around to dodge around the χ-Blade as it stabbed up hairs away from him. Ventus thrust his Keyblade skyward, and bright and powerful light burst forth around him.

"You little…!" Vanitas grunted and glared at him. Ventus's eyes glared back, bright and defiant as they sparkled with the light reflected in his heart. He rushed forward again, his Keyblade colliding with the χ-Blade, sending a ring of metal clashing on metal echoing across the barren landscape.

"Enough of this!" Vanitas snapped as he faced Aqua in her heart. She could feel his darkness attempting to overtake her, started to feel like a stranger in her own heart. But then, a warmth managed to find its way in, pushing back against Vanitas's darkness. Aqua smiled slightly and used that warmth to brace herself against him. She gathered her magic and aimed her Keyblade, and she vanished and reappeared behind her target, striking him with a powerful cast of ice.

"Hmph," he huffed as he skidded back. "Play time's over." He jumped up and stabbed the χ-Blade into the pillar, shattering the glass and sending them both tumbling. Aqua found herself suspended in nothingness, surrounded by the broken shards and bits sparkling like stars before going out. Darkness wound itself tight around her; Vanitas was holding nothing back now in his attempt to overtake her. She found no other choice but to use this and embrace her own darkness as well as her light in order to fight him. She took her Keyblade and light imbued it, and she rushed at him, clashing with the χ-Blade. But with a grunt of persistence, she pushed him back and knocked him off balance, earning a chance to strike him several times.

"Hyah!" Ventus grunted as he slashed his Keyblade against Aqua. Vanitas huffed and glared at him as he jumped back.

"Worthless loser," he said in a low voice. "I'm finished with you!" He raised the χ-Blade over her shoulder and swung it forth, creating a powerful gust of wind that sent both Ventus and Mickey tumbling. Ventus let out an agonizing groan, the breath knocked from his body as he slammed into a rock pillar. Mickey, meanwhile, was nowhere to be seen.

Ventus slid down, dazed and trying not to black out as pain wracked his body, his Keyblade barely held in his limp hand. He panted as he tried to collect himself.

"What's wrong?" he was barely aware of Vanitas's taunt. "Giving up already?" Ventus raised his head to look up at his friend and the dark creature that possessed her. He reached down and took in hand the Wayfinder that Aqua had given him before he set out on his journey.

"Aqua," he breathed. "Terra, please…" His fingers closed around the charm. "Lend me your strength. Help me put an end to this." He took the Wayfinder and brought it close to his chest. "You're my best friends. Let me protect you." He looked at it and blinked as it glowed briefly, and his eyes widened as a light enveloped his Keyblade. Along with it, newfound strength spread through his body with a familiar warmth he hadn't felt since before the Mark of Mastery exam. He jumped to his feet and hurried back up the incline.

"You just don't know when to quit, do you?" Vanitas inquired as he readied the χ-Blade in Aqua's hand. Ventus ignored him and flipped his Keyblade into a normal grip, and he cried out as he struck for the χ-Blade and struggled to hold his ground as Vanitas pushed against him.

Aqua could see traces of concern starting to appear on her opponent's face. But at the same time, she could feel the impact of the battle on her body, and her muscles were exhausted and in near agony. She summoned the last of her energy and rushed for him, and she struck him time and time again until the χ-Blade was knocked from his grasp.

Ventus, meanwhile, let out a loud yell as he redoubled his strength and pushed back against Vanitas. His Keyblade cut into the χ-Blade itself, causing a wave of energy to roll off it and across the landscape.

"What?!" Vanitas demanded as the χ-Blade's bright color faded, leaving it broken, and a heartbeat later, it knocked them both back with a burst.

"How… how dare you? You're nothing! A pawn!" Vanitas nearly howled as his rage burned in his eyes, but Aqua remained strong and refused to back down. The broken χ-Blade was engulfed in strange light, and it shattered, leaving flickering trails of light and darkness in its wake. Aqua felt a strange, sick feeling in her chest, and she fought to remain strong as darkness erupted from Vanitas. He clenched his fingers as his eyes narrowed.

"Hmph," he huffed. "I'm not done with you. You may have cost me the χ-Blade, but I'll still have your precious light!" His hand thrust out and with it, darkness struck for her. She tried to bite back a cry of fear and agony, but to no avail, and darkness overtook everything.

Ventus skidded across the rock, grunting as he got back to his feet. From the broken χ-Blade came swirling lights that shot forth and scarred the ground. Ventus squinted and held his arms up, trying to block out some of the blinding light and debris in the violent winds. He peered through and found Aqua's unmoving body lying on the ground nearby. The darkness around her pulled away and vanished, leaving her back in her armor.

"Aqua!" he yelled above the noise and tried to step toward her, though the winds and chaotic light around him threatened to throw him into the air again. He started forward, launching himself off one foot and hurrying around the lights blasting across the rocks. He called Aqua's name again and picked up his pace. The χ-Blade began to disintegrate, and he glanced over his shoulder as his heart pounded in his chest. The gusts of winds sent Aqua's body flying into the air, and Ventus leapt up after her. He reached out and grabbed at her hand, though she slipped from his fingers. But then, her own hand reacted and grasped his, and relief briefly sparked in his heart. As they were thrown away from the Keyblade Graveyard, he blacked out, and held onto Aqua's hand for dear life.

The next thing he was aware of, Ventus opened his eyes to find himself drifting in a place vaguely familiar to him. He looked down to find a stained glass pillar below him, one illustrating him on one side, his eyes closed. He smiled slightly as he placed his hand over his chest. But he looked up curiously to find broken shards of glass floating above him, and his eyes widened as he saw Aqua among them. Her body looked limp, and she didn't respond when he called her name. With focus, he found he could move through the abyss with little resistance, and he made his way to her.

"Aqua?" he said softly as he came to her side, and he took her hand in his. Slowly, she turned her head to him, and his heart dropped as he found her eyes were dull, dark, and vacant. Darkness flickered around her.

"Ventus…" she barely said before closing her eyes.

"Aqua!" he shook her slightly. "Come on, wake up! You're okay. You have to be okay." She didn't respond. He frowned as he looked around, and slowly, something deep in his memory came to the surface. His heart had been fractured when Xehanort had ripped the darkness from him, leaving him with only his light, and that light had begun to slip away. A newborn heart had reached out to him somehow and mended him, enabling him to survive and recover.

"Vanitas stole your light," he realized as he squeezed her hand. "So… that means you have only darkness now…" He shook his head. An idea started to form in his head, and he looked over to his own glass pillar. It was a stupid idea, he'd admit, but if it would help Aqua, if it would save her…

He summoned his Keyblade and took aim at his pillar. With a grunt of effort, he launched himself toward it, and the teeth of his Keyblade smashed into the glass, causing cracks to run across it. A heartbeat later, it shattered, and he felt the break within his heart. With the shards of his pillar around him, he looked up and made his way back to Aqua.

"Aqua," he said, his voice all but lifeless, and she opened her eyes again. He felt his heart reach out for her, for the darkness he was missing. She turned to him and slowly righted herself, and her hand lifted to nearly touch his face.

"Ventus… You're hurting," she said, and he nodded.

"Aqua, if you trust me, we can fix this," he told her. "If you'll be my darkness, I'll be your light." He held his hand out to her, and with a small smile, she took it in both of her own.

"Yes," she said softly. "I trust you, Ven." Bright light illuminated around them, and the shards of glass reacted and pieced themselves together below them. They both looked down as the light faded, revealing them both illustrated in the pillar, grasping each other's hands as they held their Keyblades in the others. Relief surged through Ventus's heart and he looked up to find Aqua's eyes had gained back the life he was accustomed to, and she smiled as she placed her free hand to his cheek.

"We're stronger together," she said, and he nodded.

"Yeah." He smiled as well. "You're safe now, Aqua. I'll never let anyone hurt your heart again."