Chapter 3 – The Forge of Instinct
Musutafu mornings always began in the same quiet rhythm. Steam curling from a teacup, the hum of a distant train, and sunlight slicing through the window onto Sozo Midoriya's desk. The rest of the apartment still slept, but he was already awake—cross-legged on the floor, palms resting over his heart.
He breathed in. Out.
Each breath drew that familiar hum from deep within—the heartbeat of the hydra.
When he focused long enough, the air thickened around him. Faint scales shimmered across his arms, then faded as he exhaled. It wasn't dangerous anymore. Not yet. Just a reminder that creation always wanted to push past its container.
The hydra's voice was quieter these days, more observation than command.
You are learning the pause between thought and form.
"Trying to," he murmured.
---
Deku stumbled out of his room still half-asleep, hair wild. "You're already training again? The sun barely woke up."
Sozo smirked. "And it still beat you to it."
They had turned the small park down the street into their personal dojo. To the neighbors, it looked like two kids play-fighting. To them, it was sacred ground.
Deku warmed up by stretching his fingers, glancing at the faint sigil glowing on his wrist. "Wildmutt form first?"
"Go ahead."
He transformed in a flash of green light. Fur rippled out; claws clicked against the pavement. The smell of morning dew sharpened until Sozo could practically feel Deku's senses widen.
"Okay," Sozo called, "track the metal can I tossed earlier."
Wildmutt sniffed, then bolted through the grass. He weaved between benches, nose pressed to the ground, tail lashing. The run lasted barely two minutes before the boy tripped over himself and reverted, panting hard.
"Stamina's better," Sozo said, tossing him a water bottle. "You lasted longer before instinct took over."
Deku grinned between gasps. "Still can't believe this is real."
"You earned it. Keep believing in control, not chaos."
Deku nodded, determined. Sozo could see it in him—heroic drive blooming even in childhood.
---
After Deku rested, it was Sozo's turn.
He drew the Arc's energy forward until a blue halo flickered behind him. The air pulsed with heat and frost at once.
"External Manifestation: Emberfang."
A small, red-gold creature burst from the light—sleek, feline, with eyes like embers. It hissed playfully before circling his legs.
"External Manifestation: Frostcoil."
A second shape followed, pale and serpent-like, scales shining with ice crystals. It coiled lazily around his shoulders.
Deku clapped, excitement replacing fatigue. "You made them solid again!"
"They're more stable," Sozo said, crouching. "But controlling both at once costs twice the focus."
He extended a hand toward the dirt patch in front of him. "Let's add a new one."
This time he pictured density—soil, stone, roots binding beneath pressure. The hum deepened, grounding instead of burning.
"External Manifestation: Terragard."
The ground cracked. A figure rose from it, shaped like a squat, armored beast. Brown-gray plates lined its back, each etched with glowing green veins. When it moved, the earth itself seemed to listen.
Deku whistled. "That's… big."
"Defense type." Sozo's eyes brightened. "Every creator needs a shield."
The hydra's whisper stirred. Balance is forming. Fire, ice, earth. You're missing wind—speed and freedom.
Sozo nodded, already visualizing lightness, movement, the sound of air rushing past wings.
He whispered, "External Manifestation: Zephyris."
A cyclone of pale green energy spiraled beside him, condensing into a hawk-like creature with translucent feathers. It spread wide wings, scattering dust into glittering arcs.
For the first time, four manifestations stood before him, steady and aware.
Emberfang hissed a greeting; Frostcoil flicked its tongue; Terragard rumbled low, protective; Zephyris gave a piercing cry that sent leaves spinning.
Deku's jaw dropped. "They're…alive."
"Alive enough," Sozo said, voice steady with awe. "Each one's built from understanding—matter shaped by knowledge."
He raised his hand. The four constructs faded into motes of blue light, returning to the Arc within him.
---
Training continued for weeks. Mornings for meditation; afternoons for drills.
Deku learned to fight instinct with discipline—how to think like a hero even when claws and fangs demanded otherwise.
Sozo learned precision. No longer pushing his power outward like a flood, but guiding it like a sculptor's blade.
One afternoon, while Deku practiced balancing on a rail in Wildmutt form, Sozo stood by the trees, tracing the Arc's symbols in the air. Each line glowed faintly, connecting into patterns that pulsed like circuitry.
Your control is improving, the hydra observed.
"Still feels like juggling fire."
That's because you are.
He grinned faintly. "Fair."
---
That confidence cracked a few days later.
They were sparring lightly—Deku darting in and out of Wildmutt form, Sozo testing quick summons of Emberfang and Frostcoil. It was supposed to be simple.
Then Deku lunged faster than expected. Instinct flared. The hydra inside him roared.
Scales erupted down Sozo's arms. His pupils slit. Energy crackled as two ghostly dragon heads flared behind him.
"Stop!" he shouted, but his voice came layered with a growl. Fire licked across the ground where Deku had just been.
Deku froze mid-step, eyes wide. "Sozo—!"
Sozo clenched his fists, forcing the energy inward. The hydra fought back, wanting release. He dropped to one knee, breathing hard until the light dimmed.
When he finally looked up, Deku was kneeling too, hand on his shoulder. "You okay?"
"Yeah." His voice was hoarse. "Guess my control still needs work."
Deku smiled, small but certain. "Heroes mess up too. The point is learning before someone gets hurt."
Sozo huffed a laugh. "You always have to moralize after I almost torch the park?"
"Yup."
They sat in silence for a bit, catching their breath. The smell of scorched grass lingered, faint but not unpleasant.
"I'm scared of it," Sozo admitted. "The hydra's too strong. If I stop focusing, it acts on instinct—like it's… alive."
Deku looked at him with that same earnestness that never seemed to dim. "Then maybe you have to teach it. The way you're teaching me."
The simplicity hit harder than any wisdom the hydra had offered.
---
That night, Sozo tried something new.
He summoned Emberfang first, then Frostcoil. Both hovered near, waiting for command. Instead of issuing orders, he whispered, "Show me what you are when I'm not in control."
They moved on their own. Emberfang prowled in a circle; Frostcoil curled protectively beside him. No destruction, no chaos—just life following its own rhythm.
He tried the same with Terragard and Zephyris. The four formed a loose ring around him, energy humming in harmony.
For the first time, Sozo felt balance—creation without command.
The hydra's voice rumbled low, approving.
You forge instinct into will by listening, not dominating.
He smiled faintly. "Then maybe it's time to stop treating power like a weapon."
---
Deku joined him the next morning. "You look different," he said. "Lighter."
Sozo held out his arm. A tiny hydra head formed there—miniature, translucent, curling around his wrist like a bracelet. It blinked once, then settled.
"Companion form," Sozo said. "Part of the hydra, small enough to keep me honest."
Deku crouched to look closer. "It's…cute."
The tiny head hissed softly, indignant. Deku laughed.
Sozo smirked. "Don't tell it that. It has pride."
They trained again, slower this time. More about control than spectacle. Deku learned to hold Wildmutt form longer without slipping fully into instinct. Sozo practiced summoning one manifestation at a time, keeping his emotions even.
Hours passed unnoticed.
When the sun dipped, they sat side by side on the swing set, the world quiet around them.
Deku spoke first. "We're getting stronger."
"Yeah. Strong enough to be dangerous if we forget why."
Deku kicked the dirt lightly. "Then we remember. We use what we have to help, not to prove something."
Sozo glanced sideways. "That sounds like something a future number-one hero would say."
Deku blushed. "You're teasing me."
"Maybe a little."
They laughed, the kind of laughter that only came from shared secrets and hard work.
---
Later, under the dim streetlights, Sozo lingered by the window of his room. The tiny hydra on his arm shifted, scales catching the moonlight.
"Hydra," he whispered. "We're changing, aren't we?"
Always.
The voice was deep but calm now, more companion than overseer.
Each creation teaches its maker. Each bond reshapes its core.
He watched the city below, lights flickering like distant stars. "Then maybe this is what heroes really are—people who keep reshaping the world, even when it resists."
The hydra's reply was almost a purr. You're beginning to forge instinct into will.
Sozo smiled, eyes steady on the horizon.
"And will," he murmured, "into destiny."
---
End of Chapter 3