Chapter 9 – The Dungeon Pact
The sky over Musutafu was clear when Bakugo decided to test the new kid. That's how Sozo would remember it—ordinary sunlight, children shouting across the park, and the smell of dust before things changed shape again.
Bakugo stood there with his usual swagger, hands jammed into his pockets, a grin sharp enough to cut glass. "Hey, Midoriya," he called, voice heavy with challenge. "Your cousin talks big. Let's see if he's got anything to back it up."
Sozo didn't look up from the sketchbook resting on his knee. He'd been drawing lattice patterns, trying to map the way the Adravium's glow interacted with his pulse. "You really want to spar here?" he asked, tone mild.
Bakugo cracked his knuckles. "Scared?"
The wind moved once through the trees. Deku stood between them, small and worried. "Kacchan, don't—"
Sozo closed the sketchbook. "If you want to measure strength," he said, rising, "let's do it somewhere we won't break the world."
The air around him shimmered. A line of blue light traced itself in a circle under his feet, expanding until it touched Bakugo's shoes. Then everything shifted—grass dissolving, sound thinning, the park fading into an endless white expanse.
Bakugo blinked, thrown off balance. "What the hell—"
"This is my space," Sozo said quietly. "My creation. Think of it as neutral ground."
---
A Spark and a Calm
Bakugo's grin came back, all fire. "Fine. You want a fight? You got one!"
His palms lit up with sparks. He leapt forward, explosions bursting behind him in sharp cracks. The white void swallowed the light, reflecting every flash like mirrors in fog.
Sozo didn't move until Bakugo's first blast hit. Then he raised one hand, Adravium bracelet pulsing. The explosion vanished—swallowed whole, the heat rippling over his skin and dispersing harmlessly into the air.
Bakugo stared. "You—what did you—"
Sozo stepped forward once. His movement left faint blue ripples. "You waste energy like a leaking pipe."
Bakugo snarled and charged again, explosions rapid now, wild and desperate. Sozo flowed through them—turn, slip, redirect—each blast melting into light around him.
Then, without warning, he vanished. Bakugo spun, too late. A hand rested on his shoulder, calm and unhurried.
"Rhythm, Katsuki," Sozo said near his ear. "Power means nothing without it."
Bakugo whirled, swinging an explosive punch. Sozo caught it barehanded. The flare sputtered, fizzled, and died.
The silence after was brutal. Bakugo's breath came ragged. Sozo's eyes glowed faintly with hydra light, not mocking—just measuring.
One precise push sent Bakugo stumbling back onto one knee. Not broken, just stopped.
---
The Lesson
Sozo crouched in front of him. "You think strength is noise. But the world listens better to quiet things."
Bakugo's hands trembled, palms smoking. "Shut up—"
"Or learn," Sozo cut in. His tone wasn't harsh, just final. "Those are your two choices."
The void began to tremble slightly, responding to Sozo's heartbeat. From beneath them, pale ridges rose—faint outlines of a creature coiling far below, something that moved when he spoke.
Deku swallowed. "Sozo… your dimension's reacting."
"Good," Sozo said softly. "It's time it evolved."
The ridges cracked, and light poured upward like veins under skin. The floor thickened, forming layers—living stone, breathing air. The blank void reshaped itself into caverns and tunnels.
The Dungeon was being born.
---
The Pact
Bakugo struggled to his feet, staring around at the shifting world. "What… is this place?"
"My inner world," Sozo said. "But it listens to others now. Every person who fights here adds to its form."
Bakugo looked from him to Deku, confusion flashing to awe, then irritation again. "You could've led with that, idiot."
Sozo's faint smile appeared. "You wouldn't have listened."
A long pause stretched between them, broken only by the Dungeon's low breathing sound.
Finally, Bakugo looked down. "Teach me."
Deku blinked. "Wait, really?"
Bakugo didn't meet their eyes. "I'm not losing to anyone—not even weird cousins from nowhere. So yeah. Teach me."
Sozo nodded. "Then you'll start by unlearning half of what you think you know."
"Fine."
"Good."
The ground beneath them pulsed once, as if agreeing to the new arrangement.
---
The Dungeon's First Breath
Sozo raised his hand. Blue light expanded again, carving open an entrance ahead of them—a tunnel breathing faint warmth.
"The Dungeon's alive now," he said. "Every time we train here, it'll grow. Each floor adapts to whoever enters."
Deku stepped forward, eyes wide. "So it's like… personalized simulations?"
"More like reflections," Sozo corrected. "It'll show what we fear most, and what we're meant to surpass."
Bakugo snorted. "Sounds fun."
"You'll regret saying that," Sozo said, voice low but not unkind.
They entered.
The first chamber opened like the inside of a beast—walls pulsing, faint light seeping through membranes. The air smelled of heat and ozone.
A shape began forming from the center—a creature of molten skin and crackling veins. It moved like fire given bones.
Deku whispered, "It looks like…"
Sozo finished for him. "Bakugo's anger."
---
The First Battle
Bakugo laughed, short and fierce. "Perfect."
He charged, explosions blooming from his hands, lighting the creature's face. It roared back, sending waves of molten heat. The ground hissed.
Deku, thinking fast, shifted into Grey Matter form, scanning energy output. "It reacts to his blasts! The more he attacks, the stronger it gets!"
Bakugo cursed, dodging another strike. "Then what am I supposed to do—hug it?"
Sozo's calm voice cut through the chaos. "Control. Don't fight the fire—guide it."
Bakugo gritted his teeth, taking a deep breath. He gathered his palms together, letting sparks build—not in fury, but in rhythm. Smaller bursts, measured, steady.
The creature hesitated. Its form flickered.
Deku shouted, "It's stabilizing!"
Bakugo released one focused explosion, not huge—just perfect. The molten beast shattered into dust, the room's light dimming back to steady pulse.
Sozo stepped forward, expression unreadable. "Lesson one," he said. "Balance doesn't silence power. It gives it direction."
Bakugo, panting, nodded once. "Yeah. I get it."
---
Aftermath
When they returned to the surface, the Dungeon entrance sealed behind them, shrinking back into nothing. The park reappeared, unchanged except for the faint shimmer of energy under the air.
Bakugo flexed his hands, still staring at Sozo. "You really are something else."
"So are you," Sozo said simply. "You just needed the right mirror."
Deku smiled, quiet but proud. "Guess that makes us a team now."
Bakugo smirked. "Don't push it, nerd."
But his voice lacked its usual edge.
Sozo looked toward the fading horizon. "Next time," he said, "the Dungeon will pick a new boss. Whoever wins controls the lesson."
Bakugo's grin sharpened again. "Then I'll see you down there."
Sozo nodded once. The hydra's voice whispered inside him, low and satisfied: "Three minds. Three fires. The forge grows stronger."
He let the whisper fade and watched the sunset wash the world in orange. For a moment, everything felt ordinary again—three kids standing in the light.
But somewhere, deep beneath the earth, the Dungeon pulsed like a second heart.
End of Chapter 9 – The Dungeon Pact