Tapped Out - Frank Castle x Male Reader
Summary: After a possible career ending injury, Frank's reluctant to get back in the ring with you, even if it's just to spar.
CW: MMA au - UFC au - Sparring - Brief mention of injury - MMA fighter Frank - UFC fighter Frank- Ex MMA fighter reader - Ex UFC fighter reader - Established relationship - Fluff - Slight angst
Words: 3.4k
A/N: Well I am back, and with a Frank Castle AU. I wasn't sure exactly where I was going with this but ended up deciding to go this route which I think worked out better. If this does well, maybe I'll do similar aus with other characters not hundred percent sure. I don't know crap about MMA/UFC, I've watched UFC before but not enough to understand a lot. Last thing is, uh again the warning below is just for preference, if you are fem and decided to read all I'm asking is to be respectful.
FEMALES DNI
The distant, rhythmic thud of leather hitting a heavy bag echoed in the cavernous space, vibrating inside Frank’s skull. It was a sound that used to anchor him. The violence of a fist connecting with meat, the hollow slap of a body hitting the canvas, the metallic rattle of the chain-link cage—it was the only music he’d ever cared for. Now, it just felt like a countdown to a memory he couldn't outrun.
It had been eighteen months since that night, and the guilt still tasted like copper in the back of his throat.
Logic told him it shouldn't bother him. Frank wasn't the one who’d heard his own vertebrae snap under the weight of a botched takedown. He wasn't the one who’d spent three months staring at a hospital ceiling with his jaw wired shut while a surgeon explained that his career had ended before his prime. But logic didn't account for the fact that it was you in that cage. It didn't account for the way his heart had flatlined when the referee—distracted and slow on the draw—let the extra four seconds of a dirty ground-and-pound go on far too long.
The worst part wasn't the injury itself. It was the aftermath. It was the fact that Frank’s career kept climbing, the wins piling up like a mountain, while you were relegated to a cramped apartment, watching his highlights on a flickering TV screen.
Frank shook his head, a sharp, jagged movement to clear the ghosts. He rubbed a calloused hand over his face, the stubble rasping against his palm, and stepped deeper into the dim light of the neighborhood gym.
You were standing by the weight benches, back turned to the door. Even from across the room, the sight of you hit him like a liver shot. Your posture was different now—stiffer, more guarded. The surgical scar ran like a jagged lightning bolt down the center of your spine, a permanent map of the night the lights went out.
“Took you long enough,” you said, your voice a little raspier than it used to be. You moved slowly, a careful hinge at the hips as you reached for a water bottle in your gear bag. “Starting to think you finally realized I’m a bad influence and stood me up.”
Frank didn’t say a word until he was right behind you. He didn't want to startle you, but he needed the contact like he needed air. He stepped into your space, his large, scarred hands settling gently—almost tentatively—around your waist. He pulled you back against his chest, feeling the heat of you through his shirt.
“Wouldn’t dream of it,” he grunted, the words low and gravelly against the skin of your neck. He pressed a slow, lingering kiss to the hollow there, his eyes closing as he just let himself breathe you in. “Not in this lifetime.”
You reached down, covering his rough, taped knuckles with your own hand. A small, private smile tugged at your lips as you felt the familiar heat of him. Frank didn’t just let go; he shifted, his nose grazing the ridge of your shoulder blade before he pressed a deliberate, lingering kiss directly over the raised tissue of your scar. It was a ritual now—an apology he never stopped offering, and a mark of ownership he refused to relinquish.
The sharp, salty tang of sweat clung to your skin, a dead giveaway.
“Been here a while?” Frank asked, finally pulling back. He didn't wait for an answer, already moving to drop his duffel with a heavy thud next to yours. He caught the hem of his shirt and pulled it over his head in one fluid motion, muscles rippling under skin mapped with his own history of violence. He looked you over, his dark eyes narrowing as he took in the dampness of your hair. “You said you’d wait for me. You’re gonna overwork that back before we even start.”
“I got restless, Frank,” you countered, turning to face him. You leaned back against the weight rack, crossing your arms. “Sitting around the apartment is worse for it than the gym is. You know that.”
Frank let out a low grunt, one that was halfway between a disagreement and an acknowledgment. He stepped closer, the smirk finally tugging at the corner of his mouth—that rare, lopsided Frank Castle look that he only ever saved for you.
“Is that right?” He stepped into your space, his presence looming and solid. “Maybe you just need a better reason to stay home. You sure you don’t want to pack it in? Go back, soak in a hot bath?” He paused, his voice dropping an octave, gravelly and suggestive. “I’m sure I could find a way to help you relax.”
You rolled your eyes, though the heat in your chest had nothing to do with the gym’s lack of AC. “Real subtle, Castle.”
He chuckled, a low vibration in his chest. By now, the gym had emptied out. The rhythmic snap-snap-snap of some amateur kid working a heavy bag in the corner was the only other sound, but even that was fading as the owner started dimming the overhead lights. This was the routine: the world ended at the gym doors, leaving just the two of you in the shadows of the mats, just like it had been when you were both rising stars.
You shrugged, your gaze drifting over the familiar lines of his face—the broken nose, the scars, the fierce protection in his eyes. “Maybe once we’re done here,” you said, your voice softening as you reached out to snag the waistband of his gym shorts, pulling him just an inch closer. “But I’m hoping you’ll join me. I don't think I can reach the spots that actually ache.”
Frank’s expression shifted, the playfulness dying down into something much more raw. He reached up, his thumb tracing the line of your jaw with a tenderness that would have shocked anyone who’d ever seen him in a ring.
“Yeah,” he rasped, his forehead dropping to rest against yours. “I’ll join you. But first, let's see what you’ve got left in the tank. Don't go easy on me just 'cause I'm the one still on the payroll.”
Frank paced a small circle on the mat, his movements methodical and heavy. He was staying outside your reach—way outside—dancing a perimeter that felt more like a chore than a warm-up.
Usually, sparring with Frank was like being trapped in a cage with a hurricane. He was a pressure fighter; he liked to get inside, use his weight, and make you feel every ounce of his strength. But tonight, he was a ghost.
You lunged, throwing a jab-cross combo that was meant to test his guard. Instead of parrying and digging a hook into your ribs like he used to, Frank just stepped back. He slipped the second punch with a foot of clearance to spare, his hands held high and tight, his eyes tracking your every twitch with a frantic sort of focus.
“Come on, Frank,” you grunted, resetting your stance. “I’ve seen heavy bags with more aggression than you’re showing right now.”
“Just finding my rhythm, baby,” Frank rasped, his breath hitching as he circled left. “Testing the air. Seeing how you’re moving.”
You didn't buy it. You feinted a low kick—just a twitch of the hip—and Frank practically leapt backward, his brow furrowed in a sharp line of concern. He wasn't looking for an opening; he was looking for a way to make sure you didn't break.
“Bullshit,” you snapped, dropping your hands to your sides. The sudden stillness made him stop in his tracks. “You’ve been ‘testing the air’ for ten minutes. You’re dodging hits you’d normally counter in your sleep. You’re keeping enough distance for a third person to stand between us.”
Frank adjusted his stance, his shoulders bunching. “I told you. I’m warming up. Don't want to catch you with something stupid before you’re loose.”
“You’re being soft, Castle,” you said, the words sharp and intentional. You stepped into the pocket, forcing him to either engage or retreat again. “You’re scared. You think if you put a hand on me, I’m gonna shatter like glass.”
Frank’s jaw tightened, the muscle jumping in his cheek. That hit home. He hated being called scared, but he hated the idea of hurting you more. “I’m being careful. There’s a difference.”
“Not in this gym there isn’t,” you countered. You moved in again, faster this time, snapping a leg kick that actually connected with his thigh. It wasn't hard, but it was enough to sting. “I’m not a patient in a ward anymore, Frank. I’m your partner. I’m a fighter. So stop treating me like a ghost and actually spar with me.”
Frank went still, his dark eyes searching yours. He was breathing hard, not from the exertion, but from the internal war he was losing. He looked at your spine, then back to your eyes, his hands trembling just a fraction.
“I can’t,” he admitted, his voice dropping into that raw, guttural growl. “I see you move a certain way, hear a certain sound...and I’m back in that arena. I’m watching you go down again.”
“Then watch me stay up,” you challenged, stepping into his space until your chest was inches from his. You took his hand—the one wrapped in tape and scarred from a dozen wars—and pressed it against your side. “I’m right here. I’m solid. You want to help me? Then help me remember what it feels like to be in a real fight. Don't let that guy in the arena take this away from us, too.”
Frank stared at his hand against your ribs, his fingers curling slightly. He let out a long, shaky exhale, the tension slowly bleeding out of his frame and being replaced by a focused, familiar heat.
“You’re a real pain in the ass, you know that?” he muttered, though the smirk was finally beginning to return.
“So you’ve told me,” you grinned, snapping your guard back up. “Now, quit being a coward and hit me.”
Frank grunted, a low, dangerous sound. He shifted his weight, his center of gravity dropping as he finally stepped into the pocket. “Alright. But don’t come crying to me when you’re sore tomorrow.”
“I’ll hold you to that,” you laughed, just as Frank exploded forward, finally fighting like the man you knew.
The sparring was a dance of calculated restraint. You could feel the dormant power in his shoulders every time he checked a kick or parried a strike; he was moving at sixty percent, his strikes landing with a controlled thud rather than a bone-deep crack. Even so, he was working you. He kept the pace high, forcing you to pivot, to breathe through the burn in your lungs, and to trust your body again.
But every time you threw a heavy hook that left your ribs exposed, Frank would pause for a fraction of a second—just long enough for you to recover.
"Still pulling punches, Castle," you huffed, ducking under a slow-rolling cross.
"Keeping you honest," he grunted back.
He waited for you to overextend on a lead leg kick, and then he struck. With a burst of speed that reminded you exactly who he was, Frank stepped inside your guard, wrapped his arms around your waist, and used his momentum to drive you backward. The chain-link fence of the practice cage caught you, the metal groaning under the combined weight of your bodies.
He didn't take you to the mat. Instead, he spun you around with practiced ease, pinning your chest against the cold, galvanized steel.
Frank pressed himself flush against your back, his heavy weight anchoring you there. He reached around, his large hands engulfing yours and pinning them against the mesh of the cage above your head. You were trapped between the fence and the sheer heat of him. You felt his chest heaving against your spine, his breath hot and ragged against the sensitive skin of your ear.
He didn't pull away. Instead, he leaned in, his nose brushing against the side of your neck, inhaling the scent of salt and exertion.
"You know," he started, his voice dropping into a low, vibrating rumble that you felt deep in your bones. "I forgot how good you look from this angle. Pinned up against the wire...maybe I should’ve kept you in the clinch more often."
He let out a short, dark chuckle, his lips grazing your skin. He was teasing you, trying to lighten the heavy air that had hung over the gym all evening, but there was a raw edge of hunger in his voice that he couldn't quite mask.
You felt the familiar spark of defiance—the one that had made you a contender in the first place. You didn't struggle; you waited. You felt the slight looseness in his grip, the way he’d relaxed just enough because he thought he had you.
In one fluid motion, you dropped your weight, twisting your wrists inside his hold. You used the cage for leverage, shoving off the wire and spinning into his space before he could reset his feet. Frank stumbled back a step, surprised, and you didn't give him an inch. You hooked his lead leg and shoved, using his own momentum to send him back against the fence.
You slammed your forearm against his chest, pinning him where you had just been. You leaned in close, your face inches from his, a triumphant hum vibrating in your throat.
"I don't know, Frank," you whispered, your eyes locking onto his dark, blown-out pupils. You felt the rough texture of the cage behind him and the frantic beat of his heart under your arm. "I think I like this view a whole lot better."
Frank stared at you for a beat, stunned into silence. Then, a slow, genuine grin spread across his face—the kind of grin that showed teeth.
"Yeah?" he rasped, his hands coming up to rest on your hips, no longer hesitant. "You’re gettin' cocky again. I like that.”
He didn't stay pinned for long. Frank moved with that deceptive, predatory speed he was famous for, slipping your forearm and diving for a double-leg takedown. He was careful—always careful—guiding your descent so your back hit the thick foam of the center mat with a dull thump rather than a bone-jarring crash. He followed you down, settling into a heavy side-control before transitioning into a full mount.
He didn't strike. He just stayed there, his weight a solid, grounding presence on top of you. His large hands pinned your wrists beside your head, but his grip was loose, almost a caress. He was looking down at you, his dark eyes searching your face with an intensity that felt like it was peeling back your skin. The sweat dripped from the tip of his nose onto your cheek, but neither of you moved to wipe it away.
For a long minute, the silence was absolute. Frank’s chest rose and fell against yours, his expression clouded with a question he’d clearly been chewing on all day.
"Doctor say anything new?" he finally rasped, his voice barely a whisper in the empty gym. "About...you know. Returning. Getting back in the rotation anytime soon?"
The question felt like a physical weight, heavier than Frank’s body. He knew the answer was a sore spot. He’d seen the way you flinched whenever an MMA blog posted a "Where Are They Now?" retrospective, or when commentators spoke about your career in the past tense, like you were a ghost haunting your own highlight reels. He knew the walls of that shitty apartment felt like they were closing in on you every time he left for a fight.
You shifted beneath him, the movement stiff, your eyes drifting toward the darkened ceiling. You let out a long, jagged sigh that seemed to drain the last of the adrenaline from your limbs.
"It’s hit or miss, Frank," you admitted, shaking your head slowly against the mat. "One day the specialist says the nerve ending is looking 'promising,' and the next he’s talking about 'long-term mobility management.' It’s a coin toss if I’ll ever be cleared for a sanctioned walk-out again."
Frank’s jaw tightened, his thumbs tracing small circles over your wrists. You could see the guilt rising in him again—the "why you and not me" that stayed shadowed in his gaze.
You reached up, breaking one hand free to cup the back of his neck, pulling him down just a fraction so he had to look at you. "Hey. Look at me."
His eyes locked onto yours, raw and pained.
"Even if the answer is never," you said, your voice firm despite the ache in your chest, "I’m not going anywhere. I’ll still be in your corner. I’ll still be the one screaming the loudest when you're under the lights. I’m cheering you on until the wheels fall off, Castle. You’re stuck with me."
Frank closed his eyes, leaning his forehead against yours. He took a shaky breath, the tension in his shoulders finally snapping as he let himself just be there with you, grounded by the promise.
The adrenaline of the spar had cooled, leaving behind a dull, familiar ache in your lower back and the heavy, grounding presence of Frank by your side. The gym was silent now, the lights dimmed to a low, amber glow that caught the sharp angles of Frank’s face as he watched you move.
He stood by the bench, his own bag already zipped, but he wasn’t in a hurry. He was just...observing. His gaze followed the line of your shoulders as you reached for your discarded t-shirt. You felt his eyes track the movement of the fabric as it slid over your skin, momentarily concealing the jagged line of the scar he’d kissed only an hour before.
Frank had a way of looking at you that made you feel like the only solid thing in a world made of smoke. It wasn't just desire; it was a quiet, fierce brand of devotion that he didn't have words for.
You reached down, gathering your hand wraps and your bottle, stuffing them into your duffel bag with a tired precision. When you finally zipped the bag shut and looked up, he was still there, leaning against a weight rack with his arms crossed, his dark eyes unblinking.
You couldn't help the small smile that tugged at your mouth. "You gonna keep staring, Castle, or are we actually leaving?"
Frank didn't move, though a shadow of that lopsided smirk touched his lips. "Just taking it in," he rasped, his voice sounding deeper in the stillness of the gym. "Making sure you're still in one piece."
You straightened up, slinging the heavy strap of your bag over your shoulder. The weight made you wince—just a flicker of a shadow across your face—and Frank was off the rack in a second, his hand reaching out as if to catch you, before he forced himself to go still.
"Hey," you said softly, reassuring him. You stepped into his space, tilting your head. "That bath...is it still on the table? Or were you just talking big to get me off the mats?"
Frank’s expression softened, the intensity in his eyes shifting into something warmer, more intimate. He reached out, his thumb brushing a smudge of gym grime from your cheekbone. "Always on the table. Hot water, some of those salts the doc recommended. I’ll even handle the heavy lifting."
You laughed, the sound echoing lightly against the high ceiling. "I think I can manage to sit in a tub by myself, Frank."
"Didn't say you had to do it by yourself," he countered, his voice a low, gravelly rumble.
You hummed, the sound vibrating in your throat as you reached up. You grabbed the lapels of his jacket, pulling him down toward you. Frank met you halfway, his large hands coming up to cradle your face with a tenderness that always felt like a secret he was sharing only with you.
You leaned up on your toes, pressing a lingering, salt-tinged kiss to his lips. It wasn't a quick goodbye; it was a promise. He tasted like grit and determination, and when he pulled back, his forehead rested against yours for a long, quiet breath.
"Come on," he muttered, finally taking the bag from your shoulder despite your mock protest. "Let’s get you home.”
