King's Key: The Four Prongs (formerly "Past and Present: An Ichirukia Fantasy")
Spoilers: Assumes knowledge of events up to midway in the Hueco Mundo/Arrancar arc. My own take, though, a "road not taken" approach before the fight in the Real World.
Disclaimers: The story is mine, with borrowed background from the manga. The characters are from the incredible imagination of the manga god Kubo Tite. I am in awe.
Hueco Mundo. She was running, nearly out of breath. She had to get back to the others. She knew from the reiatsus emanating from the building ahead of her that Ichigo was fighting Ichimaru Gin inside. But there was something else. Aizen. He was watching, waiting. Planning. Something was wrong. She couldn't run fast enough.
"I have to stop him," she thought.
A cavernous room. Columns supported an immensely high ceiling. Here and there, some of the columns were strewn across the floor, like discarded chess pieces on the squares of black and white tile.
Two men fought in the center of the room, one dressed in white, the other in black. The air was thick with the smell of sweat and blood. Bits of columns lay in a circular pattern around the men, the broken pieces forming something of an ad hoc arena. Two swords glinted in the sunlight that flooded the room's high open windows.
The shinigami wiped blood off his chin and pushed his strawberry hair out of his eyes. "I don't have much reiatsu left," he thought, "I need to finish this now."
Ichimaru Gin laughed, "You're tired, Kurosaki-kun. It's over."
Ichigo took a deep breath and put his hand to his face. "Please let it be enough," he thought, "I need to find the others and get them back safely."
He felt the familiar coldness cover his skin as he withdrew his hand. He was used to the sensation now, but he still disliked it. It was as if he was sharing someone else's body - someone he did not fully trust. The other Ichigo. Dark and cold. Not human. A hollow.
"You're right, Gin, it is over!" shouted the hollowized Ichigo, as he lunged, blade pointing at the man who used to be a shinigami captain, "I don't have time for this." The two zanpakutos met with a palpable rush of energy and both men sprang back.
"Damn," muttered Ichigo, grounding himself for another attack. And then, through the haze of battle, Ichigo felt it. Another reiatsu. No, two reiatsus. Rukia and Aizen.
Fear flashed through his mind. Fear for her, above all else. Over his shoulder, Ichigo saw the figure of a man - a powerfully built man dressed in white, zanpakuto held high and aimed directly at Ichigo's back. There was no time to turn and defend himself against the Aizen's strike.
"Bastard," thought Ichigo, "he's trying to stab me from behind!"
At the same time, Ichigo saw Rukia, a tiny figure in black, moving quickly to that space between Ichigo and Aizen. She hadn't had time to draw her weapon.
"Rukia, no!" he yelled, desperately looking for a way to insert himself between the two. She fell, silently, with the grace of a wounded bird. "Rukia!"
Gin quickly withdrew into the shadows with a delighted grin on his face. Aizen laughed.
"They planned this all along," thought Ichigo.
To attack from behind while he fought Gin was unfathomable, dishonorable. True shinigamis always fought each other one on one. But, this was Aizen, after all, and he clearly wanted Ichigo dead.
Ichigo had never felt such fear and such anger. It rose up in him with such bile that he nearly doubled over from the force of it, and he felt that familiar presence creep into his mind, "Let me kill him, King! I will make him suffer." Blinding rage encompassed him, and Ichigo could think of nothing more than running his zanpakuto through Rukia's attacker.
"I have to go to her," Ichigo thought, "I have to get her out of here." He had to focus, to regain control. The mask shattered. He could think clearly again.
And then, seemingly out of nowhere, he saw there were other people in the room - dressed in black, blades held ready. Shinigami.
"We'll take it from here, son," said a familiar voice.
"Dad?!! What…how…?" Ichigo struggled to form the words.
Kurosaki Isshin's eyes met his son's. Gone was the idiot smile and self-deprecating manner of the man Ichigo knew from his childhood. Isshin now wore the expression of a man ready to do battle.
"You're too weak to fight," Isshin ordered, "get her out of here."
Dazed and barely comprehending, Ichigo nodded stupidly and ran over to the place where Rukia had fallen. She was pale, a deep wound to her shoulder and chest. Her eyes were open, looking at him.
"Why, Rukia?" he asked.
She smiled and answered, "My turn to rescue you."
And then he felt it. She was gone. He had failed to protect her. Again. His screams were drowned out in the chaos of the battle that surrounded them. Tears stung his eyes.
Chapter One: Guilt, Again
She could hear birds. "I'm not dead," she mused silently. She tried to open her eyes, but they were too heavy. There was no pain, just a sensation of peace and floating. She tried to speak, but no words formed. She could hear voices, both near and far away, some of which she could understand.
"How is she?" said a voice. She knew that voice. Renji. He spoke quietly, purposefully. A second voice, slightly hoarse, answered, "They don't know if she'll live. I couldn't do anything."
"Idiot! Stop wallowing. It wasn't your fault."
She was floating again, at peace. And again there were voices, hushed and somber, "Ichigo. You haven't slept since you brought her back, have you?! You haven't eaten."
"All these years, Dad…Why didn't you tell me you were a shinigami?!" His voice betrayed exhaustion.
"I wanted you to have a normal life. I was going to tell you when you were older, but after Masaki died, I…" Silence, and then later, "How's Rukia?"
"Her wounds are fully healed, but her reiatsu is fluctuating and it's getting weaker… Unohana doesn't know why."
Nighttime. Ichigo was fighting to stay awake. It had been three days since he had returned from Hueco Mundo carrying Rukia. Chad and Uryuu had taken Orihime safely back to the Real World. The rest of the shinigami had escaped with surprising ease and had returned to the Soul Society shortly after Ichigo.
Ichigo had refused to leave Rukia's side, even as Captain Unohana treated her. He had expected Unohana to object, but she had not. Maybe it was the fierce look in Ichigo's eyes that had greeted her when they arrived at Division Four's clinic, or maybe Unohana just understood his need to assuage the guilt he felt.
Other than the bed in which Rukia lay, the room was spare. A few chairs, a small table. The window was open, and a light breeze brought in the cool night air. Byakuya had arrived shortly after Ichigo's return, and had stood stiffly at Rukia's side for most of that time, eschewing multiple offers to be seated. A short while earlier, Byakuya had been called away on official Gotei business. He had not yet returned.
Ichigo felt a sense of relief when the elder Kuchiki left. Attempts at conversation had not gone well, and Ichigo felt Byakuya blamed him for what had happened to Rukia. Not that it mattered. Ichigo blamed himself.
Ichigo's unease grew with the unexpected appearance of his father at Rukia's bedside. Ichigo had always viewed the Real World and the Soul Society and their inhabitants as separated. People belonged in one world or the other. He, Ichigo, was a visitor to the Soul Society, just as Rukia was a visitor in his world. Now, the lines were blurred. The apparent duality of his father's existence left Ichigo feeling uncomfortable.
Rukia lay on the bed, silent and still, the only sign that she clung to life was the gentle rise and fall of her chest beneath the sheets. She looked so tiny and frail. Rukia, to whom Ichigo had looked for strength when he was at his weakest. Rukia, who had always been there to straighten him out when he needed a swift kick. He felt her slipping away from him. And it was different this time. This time, there was nothing he could do to save her. No rescue. Nothing to do but wait. The thought made him restless.
Ichigo stood up and paced the tiny room as he had many times before. He was exhausted, but he willed himself to stay awake. "I need to be here when she wakes up," he thought.
Realizing that he was clenching his fists so hard he had started to draw blood, Ichigo took a deep breath and resumed his vigil on the chair next to the bed. Rukia's hands were folded over her chest, and Ichigo instinctively took one of her hands in his. It was cold and small. He covered her hand in his, willing the warmth from his hand to hers. Minutes, then hours went by as he held her hand. In spite of himself, he drifted off to sleep, succumbing to the breeze, the smell of evening, the comforting feel of her hand in his. He dreamed that her hand squeezed his.
Ichigo awoke with a start. It was early morning. "You look terrible," Rukia said in a voice that was strong and clear, "Slacker. Was Gin that hard on you?" He stood up abruptly, releasing her hand and feeling awkward.
"Rukia." It came as more of a rasp than anything else. Heat rose in his cheeks. Not wanting her to see his face, he quickly mumbled something about getting Captain Unohana and all but ran out of the room.
Out in the hallway, Ichigo leaned against a wall and briefly closed his eyes. As relief flooded his body and he suddenly felt very tired. He barely registered the presence of several of Unohana's staff coming towards him as the hallway dissolved into blackness. He felt himself fall.