A/N: I don't own Bleach or its characters but that should be obvious.
He silently pulled on his hakama in the darkness, and he craned his head behind him and watched her sleep as he dressed. Her inky mullet was spread over her pillows like a halo, and he had folded the long tail behind her when he got up. He had run his fingers through those locks just an hour ago, tugged at them as they breathed together, and she was pressed up against him just a few minutes ago, head on his chest and fist on his ribs. And just an hour ago, she had held onto him for dear life and whispered soft, sensual words in his ear like she had done it for decades.
He pulled on his kosode, whipped his arms through the sleeves and nearly hit himself in his haste. He would miss her, he thought. He would miss her touch, and her laugh, and her sharp tongue. But he made a mistake. He made a mistake as soon as he acknowledged her weeks ago. He made a mistake when he let her to take him to her house for dinner, and his effort to visit her everyday after that was a mistake, and for him to lay her across her bed and do things that then made him blush was a huge mistake. But his biggest mistake? His biggest mistake was to fall in love with her.
And she was the one who had to bear the consequences of his mistake.
"Stop," he heard, and he froze in the windowsill. He looked back, and he saw that she had sat up and squinted blearily at him as she ran a hand through her shaggy hair. "Where are you going? Are you really gonna leave at three in the morning? Go back to bed, Renji, you can be embarrassed at a decent fucking hour." She said lamely.
He opened his mouth to speak, but the words seemed to stick in his throat like phlegm, and he watched her frown. And it hurt him when she did that, he thought, because she looked hurt and she didn't deserve a scumbag who'd hurt her. "Renji, are you leaving? When will you come back?"
"I..." He cleared his throat and his ribs expanded as he inhaled. "I don't know…" He answered softly as the air rushed out from between his lips, and the look she gave him, confused and almost vulnerable, almost broke his heart. "I'm sorry."
"Promise to come back. Promise me, Renji."
That broke his heart, he thought, and the dread of all his mistakes hit him like a wall of bricks, and he was almost ill. "I-I can't do that." He responded. "I'm sorry, but I can't you promise that. This was a mistake, and I'm sorry. You're a child, and I'm… not. I made a mistake, and I'm sorry, because it'll affect you more than me."
She scoffed and chuckled, and she rubbed her hands over her face. "No. It'll affect you just as much. You're the type which stuff weighs on you for years and years, and you won't forget about me because of that, ever. You haven't made a mistake, not yet. But you will if you just leave."
"Tatsuki, I broke the law-"
"So's that Hitsugaya guy, he's been visiting Karin every weekend almost. And that girl with the braid sneaks into Uryuu's room every chance she gets. The Soul Society can't be oblivious to them. They break the law, but they sure as hell aren't getting much punishment. The mistake would be leaving, because we'd both only end up hurting in the end."
"It's-... you're a child, barely twenty. I'm nearly seventy years old."
"Karin's sixteen, and she's told me that Hitsugaya is in his forties. Rukia's sixty, and Ichigo's only twenty. Age doesn't seem to matter much."
He opened his mouth, and then shut it. "I just… can't."
"Why? Has the last six months been a lie? All those late nights and flirty jokes and wrestling matches and soft kisses? Have you really just been using me?"
He winced. "No! I'm not a scumbag!" He retorted.
"Then what am I? A bed you can lay on whenever you come to Karakura, and then forget about once you go home?" She spat.
"No! You're… you mean a lot. But I can't."
"Why?"
He licked his lips. "I… because I..."
She leaned forward and pulled him out of her window and onto her bed, and she wrapped her arms around his back and prying his lips open with her's. He automatically reciprocated and let his eyes droop shut. She was so warm, so beautiful, but it was a mistake.
He pushed away from her, propped himself up and sighed. "I- this is-"
"Why? Am I not pretty enough? Am I too boyish? Too girly? Am I not tough enough? Am I too tough? Do I not stroke your ego enough?"
"No! It's not about enough of that. It's just… wrong."
"Do you not love me then? Was the mistake letting all that testosterone going to your head and fucking me? Was I really just a fuck?"
It tore his heart to ribbons to hear her words. She knew where to hit him, he thought, and that was a mistake of his too, to drop his guard enough to let her wriggle in and see all the chinks in his armor. It'd only make it harder for both of them. "Tatsuki, you're not just a fuck, or bedding, but I just… can't."
She pushed him off of her and raked her hand through her hair, and he sat between her legs, watched her as she scratched her scalp.
"Maybe you're right." She heaved a sigh. "Maybe we were a mistake. Maybe the last six months was just an intoxicated dream. Maybe… maybe I was just too naive, and maybe you're just lonely, and maybe we were just a giant mistake."
And it broke his heart. He wanted to tell her that the weeks he spent with her had been one of the greatest times in his life, that those late nights and ice cream dates and those times when they just wrestled and rolled around in the grass would be memories he'd always keep close to his heart. But they were a mistake. He couldn't put her through sporadic visits, and he couldn't put her through the possibility of his death. A relationship would be cruel and unfair to her.
"I'm sorry." He murmured.
"Stay the night as least. Please. Just humor me this one last night, and then you can do whatever the fuck you want." She pleaded, and he sighed, because he was still so weak when it came to her, and he pulled off his sandals and crawled under her blankets, and he surrendered himself to his mistake one last night.