Honkai Star: Rail x Reader Oneshots

"I had all and then most of you, some and now none of you" | Aventurine

Summary: In a quiet moment, you confess to Aventurine that you have Entropy Loss Syndrome, a rare condition that causes you to slowly fade away as your body ages prematurely. Despite the devastating news, Aventurine promises to fill your remaining days with love and joy, vowing to make the most of every moment. As your condition worsens, Aventurine remains steadfast by your side, pouring his heart into each moment, but the heartbreaking reality of your fading existence looms over their bond.

Tags: Aventurine x Reader, Angst, Romance, Hurt/Comfort, Entropy Loss Syndrome, Terminal Illness, Love & Loss, Emotional Pain, Fading Away, Promise of Love, Vulnerability, Heartfelt Confession.

Warnings: Terminal Illness, Mentions of Premature Aging(?), Heavy Angst, Emotional Distress, Potential Character Death.

The confession came on a quiet night, the kind that invited secrets into the world with the soft glow of stars and an open sky. Aventurine leaned against the balcony, arms crossed, his silhouette framed against the city lights as he watched you approach with a faint smile. He seemed relaxed, a rare moment where he wasn’t balancing some high-stakes game in his mind. The scene felt almost too perfect, yet your heart thudded with a heaviness that disrupted the peace.

As you came closer, the warmth in his eyes softened. He took your hands, pulling you into a familiar embrace, his voice a low murmur. "Is something on your mind, love?"

You hesitated, but his gaze remained steadfast, sensing the seriousness of your expression. Taking a deep breath, you managed to find the words. “Aven…there’s something I need to tell you. It’s not easy, but… I want you to know.”

His fingers traced gentle patterns along your hand, urging you on without words. Feeling his touch strengthened your resolve, even as fear lingered at the edges of your confession.

“I have Entropy Loss Syndrome.” The words came out in a whisper, almost fragile against the vastness of the sky. “I’m…fading, Aven. Slowly, day by day.”

The silence that followed was heavy, stretching between you like an insurmountable chasm. Aventurine’s expression stilled, the playfulness drained from his face, replaced by something raw, almost wounded. His grip on your hand tightened as if afraid that letting go would mean you’d slip away.

"When… how long have you known?" His voice wavered, each word weighed down by a struggle he tried to hide.

“I’ve known for a while, but I didn’t want to burden you with it.” You looked down, unable to meet his eyes. “It’s already starting—the slowing down, the blurred edges. I’m scared of what it’ll do to me, to us.”

Aventurine swallowed hard, pulling you closer into his arms. His breath was shallow, but his hold was strong, as if his love alone could anchor you to this world. The usual confidence that exuded from him was cracked, leaving the vulnerable heart beneath exposed. “You should’ve told me sooner, you know. I… I would have been here for you every second, every moment.”

“I didn’t want to rob you of the joy you bring to my life,” you replied, your voice quivering. “I wanted to pretend, just for a little while, that we had all the time in the world.”

He let out a quiet, bitter laugh, pressing his forehead against yours. “Then that’s exactly what we’ll have.” His voice was hoarse, yet resolute, that familiar fire of determination flickering in his eyes. “Every single moment, every heartbeat—I'll be here, filling your life with as much love and joy as I can. I swear to you, I won’t let Entropy take away what we have.”

The next few days passed in a strange, precious blur. Aventurine, ever the strategist, had planned the days with a fierce intensity, filling every hour with as much happiness as he could. From sunrise strolls through bustling markets to moonlit dinners on the rooftop, he poured his heart into every moment.

But as the days went by, you felt the effects of the syndrome take hold, a little more each day. Simple tasks became arduous, your energy waning even as you fought to keep up with his relentless joy. Aventurine was always there, catching you with a steady hand and a reassuring smile. You’d find him at your side, quietly reading or humming a tune, his presence a constant comfort.

One evening, after a day of laughter and stolen glances, you felt a pang of exhaustion deep in your bones. You sank into a chair by the window, watching Aventurine as he paced the room, animatedly recounting a story from his days at the IPC. The light in his eyes was captivating, and you found yourself memorizing every detail of his face—the way his eyes crinkled with laughter, the flicker of mischief in his gaze.

Your breaths became shallow, and Aventurine noticed, rushing to your side. “Are you alright?” he asked softly, his hand warm against your cooling skin.

You nodded, feeling a bittersweet ache in your heart. “I’m just…grateful. For you. For everything.”

He looked at you, his expression unreadable. Then he knelt beside you, placing his hands over yours. “Don’t say it like that,” he whispered. “Like it’s the end.”

“Aventurine…” You searched for the right words, but all that came was a quiet, heartfelt plea. “Promise me you’ll keep living, even after I’m gone.”

His face crumpled, a tear slipping down his cheek. Aventurine’s usual facade shattered entirely, replaced by a profound vulnerability that he’d only ever shown to you. He took a shaky breath and pressed a lingering kiss to your knuckles. “I can’t imagine life without you,” he said, voice cracking. “But I’ll honor you in every way I know how. I promise.”

In the days that followed, Aventurine kept his vow, filling every precious second with a fierce, unwavering love. He carried you through the laughter and tears, holding you close as the boundary between your world and his slowly blurred. His warmth, his touch, the depth of his love became an anchor, grounding you in the moments you had left.

And as your world faded, you knew that Aventurine’s love would live on, a light that would burn bright in his heart long after you were gone.