Once Ichigo had been told the truth of his own soul, once his hollow powers roared with life (perhaps it roared with the undercurrent of death instead) Ichigo couldn't exorcise this new found relationship with his Zanpaktou.
The war ripped him apart. Sure, he succeeded in defeating the Quincy king, but at what cost? Zangetsu kept him alive and together as long as he could but in the end his soul had split. He was only human, after all.
No one knows why. It just happened.
The Gotei 13 lost many. His close friends were safe. That's all he cared about.
Ichigo shut his eyes to the bright morning sky, red tinted on the horizon for the lost loved ones. His soul hurt, a deep cavern craved in it. He felt it grow with each breath. Kisuke was kneeling beside him, holding his hand so tight they shook.
Breath coming in short gasps and pants. Gods he just wanted a lungful of air. Just enough to tell his lover it'll be okay. He'll find him again.
Except he won't. Ichigo's soul was tipped too far towards a hollow. He won't go to Soul Society.
"...King, give me to Kisuke. You're still in bankai, he can seal me until you reincarnate." But would he reincarnate?
Ichigo scoffed at the idea. No that wouldn't work. The tear in his soul was already too great, his bankai would disappear shortly.
Zangetsu made an aggravated sound, shouting, "Listen to me! Stupid King! Trust him, he knows what to do." His yelling died out to a whisper towards the end, the fire fueling his hollows anger dissipated and turned to concern when Ichigo tensed in pain. Eyes clenched shut and teeth gritted together as wave after wave of pain rippled through his body.
He barely heard Kisuke's shout of panic, his reiastu no longer able to be controlled and roiled around him in shades of black tinted with red. With a yell of "Seal him!" Ichigo thrust what remained of Zangetsu's Khyber blade in Kisuke's grasp and felt darkness take him under.
Kisuke watched the cars drift by on this gloomy afternoon. Only person he'd long to spend this type of day indoors with long since gone.
Kisuke promised his love so long ago that he'd watch over Zangetsu but told him not to keep his Zanpakuto waiting too long. the teasing fell on deaf ears that dreadful day. Tears had blurred his vision through the sealing kidou he wrapped around what remained of his loves soul.
It had been a good two decades since then. But still hurt like it had happened but a moment ago. He still wakes up in the middle of the night, panicked steps rushing to Zangetsu's sealed form just to make sure he was still there.
He could feel the spirit sleeping under his palm when laying a gentle hand on the bindings. A pang of sorrow would over him sometimes. Zangetsu was, too, suffering without his wielder but wasn't awake to fully feel it.
Getting up from the park bench, Kisuke made his way back to his home. The Shouten still sat like it did all those years ago. New barriers in place but not changed. The sliding door swung open with a clack. Jinta, still short as ever, yelling throung pants, "The swords gone!"
Kisuke froze mid step.
His body moved before his mind caught up. If Ichigo is truly back then why wasn't he here with Kisuke?
"You know where he is, don't pretend. Foolish boy." Beihime chided in his mind. Yes, he did know. That's why his body was flash-stepping to the very spot without his consent.
The rare moment the sun shone through today's gloom was, of course, the only time it wasn't really needed to brighten Kisuke's day.
There, sat crossed legged at the swelled river that took his mother way, in his shinigami shihaksho with his strange x shaped armor, was Kurosaki Ichigo. Bright orange hair a little longer than the last time he'd set his sight on the younger man. It suited him.
Zangetsu was materialized beside Ichigo, arms crossed over his chest deep in thought. The two painted a picture of danger.
"Been awhile, geta-boshi." Ichigo's voice sounded rough from disuse. Zangetsu was now turned and staring at him with what appeared to be gratitude, but something deeper underlying his eerie gaze...like he was in pain.
"It sure has, Ichigo." Kisuke crossed the few steps that separated them. Placing his hand on Zangetsu shoulder, squeezing gently then knelt and wrapped his arms around Ichigo. The familiar warmth of the youth a comfort, his unique scent of sandalwood and vanilla drifting to his senses.
Ichigo leaned back into his warm chest, placing his hands atop Kisuke's arms.
They sat there until the clouds moved in closer, the promise of rain lingering in the air.
“I’m sorry I took so long coming back. I tried to rush it. To force my soul back together and will it to mend. Zangetsu told me I was reckless in doing that.”
Ichigo smiled softly at his hollows input, “I...all I felt was his pain. Or maybe it was mine. Where I was felt like nothing, and yet everything. I couldn’t let him continue to be in pain for my sake. You understand right, Kisuke? He’s always been there for me even though I thought of him nothing more than a outsider but deep down I always felt he belonged there. I wanted to apologize. And I did. We were talking before you arrived.”
Yes, Kisuke understood. He had fought his own Zanpakuto a very long time ago. His oldest friend. To repair a relationship like the one with your own soul was a feeling he couldn’t put into words. Freeing, maybe the right one. The weight of fighting with a heavy heart and a soul that wasn’t in sync cut deep. He never wanted to feel it ever again. “And you won’t. Stupid boy.” Kisuke smirked at the insult (endearment).
“How are you feeling, Ichigo?”
“Liar. Your soul is still suffering and your in pain.” Zangetsu interrupted Ichigo’s reply.
Kisuke feared that. Rushing as he did did not repair his soul completely like it would have if it remained dormant for longer.
But no one has ever spilt their soul in half and return 20 years later with memories intact and with the same sword spirit. His best guess is it just needed more time to heal like any wound.
Ichigo hunched foreword, breaking Kisuke’s hold. The younger man struggled to stand. He could see the pain was great, making his legs shake. Before he could help though, Zangetsu had moved to his wielders side, baring as much weight as he possibly could.
“Ichigo, you shouldn’t of rushed things. A soul is a very delicate, yet very strong piece of ones being.” Ichigo growled, the sound not entirely human. “I had to! I couldn’t keep waiting in...in whatever I was in knowing I’m hurting my own Zanpakuto! I had to come back and make him whole.” Ichigo nearly collapsed with the outburst if not for his hollows tight grip on him.
They weren’t facing him. In fact, he hadn’t seen Ichigo’s face at all yet.
As if sensing Kisuke’s question, Ichigo’s shoulders tensed and Zangetsu gazed over his shoulder at the older shinigami.
“Ya know he was gonna ask sooner or later, King.”
Ichigo sighed. “I know.”
“Ichigo-“ He was cut short at the sight of Ichigo’s eyes. The once honey brown now matching his hollows. War streaking down his face where his masks usually sat. The beginnings of a hollow hole forming in his sternum.
He was turning into a hollow.
So after all this time it still approached like a brewing storm. Would he lose his mind? Would he still remember his family and loved ones?
“Zangetsu is trying to keep the transformation from consuming me. But he can’t stop it from happening.”
Kisuke hesitantly reached out to run his fingers over the marks on Ichigo’s face. They felt strangely cool to the touch. “This is why you were in pain.” He looked at the hollow.
“Yes. King was still human when his soul died, I tired to keep it from what was left of his soul. I’m not sure what’ll happen if I let go. Being half hollow shouldn’t of corrupted his soul beyond death. It should of just made us stronger.”
“Maybe I can help,” Kisuke could keep them contained at least, so he offered. “Come back to the Shouten, we’ll figure this out.”
Ichigo shook his head and stepped back with Zangetsu. A garganta splitting the sky behind them. “I can’t Kisuke. I’m sorry.” He jumped back into the void, tears falling silently down his hollows marks. Once they stepped foot on a reishi made bridge, he closed the garganta, Kisuke’s heartbroken gaze the last thing he saw.
Ichigo took in a shaky breath, sonido-ing to the end. Their speed increased, he felt stronger but still felt like the wrong move would shatter his mending soul. He should of listened to his gut and stayed dormant longer.
Once he stepped foot on the white dunes of Hueco Mundo pure unadulterated agony ripped through his core. The hollow hole opening fully. He screamed until his throat tore and mended again and again.
Zangetsu had let go.