Chapter 17: His Plan
The door clicked shut behind Izuku, a sound both soft and final. The interrogation room was a sterile, silent box. Mnemosyne looked up from his spirals, his watery eyes focusing. A slow, delighted smile spread across his face.
“Ah! Deku!” he chirped, his voice oddly melodic. “You’re here! Of course you are!”
BREATHE KATSUKI. JUST BREATHE. FOCUS ON THE SPACE BETWEEN ACTION AND REACTION. BREATHE.
That’s what Bakugou kept saying to himself at least. Trying his best to keep himself under control as he watched Izuku. He sat himself down on a swivel office chair, gripping the armrest as he leaned back, silent but eyes sharp. BREATHE. FOCUS ON THE SPACE BETWEEN ACTION AND REACTION. Aizawa noticed. Everyone on that side of the glass noticed. Wasn’t he supposed to be the one pacing and trying to blow stuff up? Aizawa just took mental note, nodding to himself as he observed Bakugou’s actions and control.
When Izuku walked into the room the villain's face lit up. “Ah! Deku!” He used his hero name. BREATHE. “You’re here! Of course you are!” JUST. “Is Dynamite here too?” BREATHE. “Did he come with you?” FOCUS ON THE SPACE. “He’s coming in right?” BETWEEN ACTION. “Of course he is he’s Dynamight. He’ll want in on the action” AND REACTION.
Izuku pulled out the chair opposite the villain, the legs scraping faintly on the floor. He sat, folding his hands on the table. Calm. Open. “It’s just me today.”
Mnemosyne’s smile didn’t falter, but his eyes flickered, just for an instant, to the one-way mirror. A predator sensing a hidden presence. “Pity. He’s the more… volatile canvas. The contrasts are sharper. The fall from a greater height is so much more dramatic, don’t you think?”
“You talk about this like it’s art,” Izuku said, echoing the psych profile. His voice was neutral, curious even.
“It is art!” The villain leaned forward, his cuffs rattling. “The most profound art! I don’t create crude puppets or mindless thralls. I craft… experiences. I take a moment of perfect human purity—joy, trust, love—and I show its hidden architecture. The fault lines. I let the subject build their own collapse. It’s collaborative.”
Behind the glass, Katsuki’s grip on the armrest tightened. The synthetic leather creaked under his fingers. Collaborative. This freak was calling the violation a collaboration.
“The seed you mentioned,” Izuku pressed, ignoring the philosophy. “How does it work? Is it a specific memory?”
“Oh, it’s so much more elegant than that.” Mnemosyne sat back, admiring his own narrative. “A memory is a flat thing. A recording. I implant a… a principle. A rule of transformation. Think of it as a tiny, perfect machine. It lies dormant, fed by your own contentment. The happier you are, the more potent it becomes. And then, when that happiness peaks… click. The machine activates. It doesn’t erase the happy memory. It infects it. It asks the brain a single, terrible question: ‘What is the worst possible thing that could be true right now?’ And the brain, magnificent organ that it is, provides the answer. From your own deepest wells. Your own private fears become the new reality of that moment.”
The clinical description was worse than any boast. It was a blueprint for psychological torture. Kirishima muttered a low “Jesus,” behind Katsuki.
Izuku’s expression remained studiously placid, but a faint tension had appeared in his jaw. “And the trigger is proximity-based? Through your… vector?”
Another gleeful smile. “You’ve done your homework! Yes. My good friend at your building. A humble artist himself. He simply… delivered the catalyst. A handshake for you, a brush of the shoulder for Dynamight. The seeds are in the soil.”
“And they’re in both of us.”
“Naturally! It’s a duet. Your moments are intertwined now, aren’t they? The trigger is shared. One’ peak affective state’ will likely catalyze the other’s. A symphony of despair!” His eyes glazed with fanatical joy. “I wish I could be there to witness it. To see the exact second the peace shatters and the horror blooms. Will you scream? Will he?”
The space between action and reaction.
Katsuki’s vision tinged red at the edges. His breathing was a forced, mechanical in-and-out. He could feel the heat building in his palms, a dangerous feedback loop of rage and fear. He pictured the morning. Izuku in his sweatshirt. The freckles. The quiet. That was the soil. This monster had planted a bomb in it.
“You won’t see anything,” Izuku said, his voice hardening for the first time. “You’re here. It’s over.”
“Is it?” Mnemosyne laughed, a dry, rustling sound. “The art is already created! The installation is complete. I’m merely the curator now. The work exists independently of the artist. That’s what makes it pure.”
He tilted his head, bird-like. “Tell me, Deku… what do you think Dynamight’s ‘worst possible thing’ might be? I have my theories. For a man who builds his identity on control… is it losing it? Hurting someone he… values? Or perhaps,” he whispered, “it’s being seen, truly seen, and then deemed worthless. A rejection from the one person whose opinion he secretly fears.”
Every word was a needle aimed precisely at the cracks Katsuki had spent a lifetime cementing over. The villain wasn’t guessing. He’d studied them. Profiled them. The fake concierge hadn’t just delivered a catalyst; he’d been a scout, gathering data on their routines, their interactions.
Izuku stood up abruptly, the chair legs screeching. “This interview is over.”
“So soon? And we were just getting to the interesting part!” Mnemosyne called after him as Izuku turned toward the door. “You should be more concerned about your own seed, you know. For the Symbol of Hope… is it failure? Powerlessness? Or is it something simpler? Is it being the cause of his ruin?”
Izuku froze, his hand on the door handle. His back was rigid.
Behind the glass, Katsuki was on his feet. The chair had rolled back and hit the wall. The mantra was a silent scream in his head, barely holding back the dam. Don’t. Don’t give him the reaction. He wants this. He wants you to break.
Aizawa placed a firm, grounding hand on Katsuki’s shoulder. “He’s baiting you. Both of you. Right now.”
“I know that,” Katsuki snarled through gritted teeth, but he didn’t shake the hand off. The contact was an anchor.
Izuku exited the room, the door sealing the villain’s smiling face away. For a moment, he just stood in the sterile hallway, taking a deep, shuddering breath. When he re-entered the observation room, his calm was paper-thin, his eyes a turbulent green.
“He’s told us everything he wants us to know,” Izuku said, his voice tight. “Which means he’s hiding something else. The trigger isn’t just ‘happiness’. There’s a specific condition. He’s too proud of his ‘art’ to not have a specific, poetic condition.”
“The shared aspect,” Kirishima said, rubbing the back of his neck. “He kept hammering that. A duet. Your moments are intertwined.”
A cold realization dripped down Katsuki’s spine, cutting through the heat of his anger. He looked at Izuku, and saw the same dawning horror reflected back at him.
The shared trigger. Their peak affective state.
It wasn’t just about being happy.
It was about being happy together.
The “seed” was designed to poison the very thing they couldn’t admit they were building. It was a weapon crafted for the “in-between.” The villain hadn’t just targeted two top heroes; he’d targeted the fragile, unnamed connection between them, aiming to turn its first real bloom into a permanent rot.
The silence in the observation room was thick, choked with the unspoken implication. Aizawa’s dark eyes moved between them, understanding far more than he would ever say.
“We need to find that vector,” Aizawa stated, breaking the tension. “He’s the only lead to possibly reversing this. Every second he’s out there is a second he could activate it remotely if he has a dead man’s switch.”
But Katsuki wasn’t listening to the logistics anymore. He was staring at Izuku, at the pale, determined set of his face. The fear wasn’t for himself. It was a mirror.
The villain’s final question echoed. Is it being the cause of his ruin?
Mnemosyne had given them the rules of the game. They were now trapped in a cruel race: find the vector and disarm the threat, or risk having their first real moment of mutual, acknowledged peace become a weapon that destroyed them from the inside out.
The space between action and reaction had never felt so narrow, or so charged with potential devastation.
The space between action and reaction had never felt so narrow, or so charged with potential devastation. It snapped.
Katsuki turned and walked out of the observation room.
He didn’t look at Aizawa or Kirishima. He didn’t look at Izuku. His boots struck the polished floor in a rapid, retreating rhythm that was just shy of a run. The sterile hallway blurred past him, a tunnel of muted grey and harsh fluorescent light.
“Kacchan?” Izuku’s voice called from behind him, confused.
He didn’t stop. He hit the stairwell door, shoving through it instead of waiting for the elevator. The concrete steps echoed with the frantic, chaotic beat of his descent. Two floors. Three. His breathing was harsh in the enclosed space, not from exertion but from the panic clawing its way up his throat.
He burst out into the secure parking level, the cooler air hitting his heated face. His car was a dark shape in the distance.
Footsteps pounded behind him, gaining. “Kacchan, wait!”
“Go back, Deku.” The words were a low growl, thrown over his shoulder. He fumbled for his keys, his hands uncharacteristically clumsy.
“Talk to me! What’s wrong?” Izuku caught up, reaching for his arm.
Katsuki whirled, yanking his arm away as if burned. The motion was violent, sudden. The raw fear on Izuku’s face—the concern, the openness—was a physical blow. It was the exact thing the villain wanted to poison.
“Stay the fuck away from me, Deku.”
The words were flat, cold, and absolute. They hung in the damp underground air.
Izuku flinched as if struck. “What? Why?”
“Because you heard him!” Katsuki’s control fractured, his voice rising to a shout that bounced off the concrete pillars. “It’s a shared trigger! The better it is, the worse it gets! Don’t you get it? Every time we— Every damn time we’re…” He couldn’t say it. He gestured wildly between them, his hand trembling. “We’re fueling it. We are the goddamn trigger!”
He saw the understanding dawn in Izuku’s eyes, followed immediately by a stubborn denial. “So we don’t play into it! We find the vector, we fix it. We can’t just—”
“We can’t just what?” Katsuki took a step back, creating a chasm of asphalt between them. “Risk it? You want to roll the dice on that? On having some… some implanted nightmare tear through your head because we couldn’t keep our hands to ourselves? Because we had a nice fucking day?” He laughed, a sharp, broken sound. “He wins if we do. He wins if we don’t. The only move is not to play.”
Izuku stared at him, his expression crumbling from confusion into a pained realization. “So that’s it? You’re just… leaving? After everything? You’re going to let him dictate this?”
“I’m not letting him dictate anything!” Katsuki roared. “I’m removing the variable! I’m taking his damn canvas away!” He was breathing heavily, his chest tight. The truth was a sick, heavy stone in his gut. He couldn’t ruin everything. He couldn’t be the one to shatter it all, to see that peaceful morning in Izuku’s eyes overwritten with some personalized horror he’d inadvertently caused.
He couldn’t bear the thought.
So instead… he’d avoid him.
“This is cowardice,” Izuku said, his voice quiet but clear. It cut deeper than any shout.
“It’s tactics,” Katsuki shot back, turning finally to wrench his car door open. The interior light made a stark pool on the ground. “It’s the smart play. You want to be a hero? Then be smart. Stay away from me until this is handled.”
He slid into the driver’s seat, the door a solid barrier. Through the window, he saw Izuku still standing there, rooted to the spot, his figure growing smaller and more distant as Katsuki reversed with a screech of tires. The last thing he saw was Izuku’s hand, half-raised, then falling limply back to his side.
Katsuki hit the accelerator and didn’t look back.