Shoutout: A big thanks to Droid, who has kindly offered his services as the story's beta reader!

He Who Protects

Chapter 15

Empyrean whispers chittered from the shadows blanketing the cavern's corners. Foul warp energies flowed in invisible, chaotic eddies about the space. Forces of the aether probed his mental shields. Pathetic attempts to break and ravage his mind.

A dull, golden glow flickered to life atop his skin. The ancient voices of Chaos retreated but they didn't stop their ceaseless muttering.

"The Imposter deigns to visit me." Overhaul tutted and jumped down from the raised dais. "Tell me, did you actually see the Carrion Lord hiding on his throne? Or did he force this on you?"

Yellowed teeth poked out from the black plague mask. A foul odour emanated from his corrupted body. Titters and aetherial currents surrounded Chisaki and made Izuku's skin crawl.

Izuku fingered his sword's hilt. His eyes narrowed and he sank into a small crouch.

"I am here of my own volition, traitor," he hissed. "I will finish His work and see you purged."

Polyphonic laughter spilled from Overhaul's throat, brushing against his mind with sadistic glee. Pin feathers rippled over the villain's skin in a muti-hued haze of mind-addling change.

"He could have been a god, you know?" Overhaul brought his taloned hand up in a fist of flashing death. "But He decided to walk amongst men instead. A pity, really."

Izuku spat and his fingers curled round his sword's hilt. "How so?"

"He could have been so much more than a boy playing hero." Chisaki's claws clacked together in flashes of mist. "Tzeentch knew it… He feared it. Now I, Tzeentch's greatest warrior, will have the honour of killing the Emperor of Mankind and I will ascend."

"You will try."

White flames sizzled the air in an elegant arc of flickering destruction. Steel glimmered beneath the fire coating the blade. Izuku levelled the blade in front of him, pointing it at Overhaul's chest.

'I can't use too much power. Not yet.' Izuku tensed his legs. 'I can only hope my guess that his quirk has yet to be corrupted holds true. I'll feel him out.'

Fire burned the air as Izuku leapt forward with a yell. Overhaul smiled, his body shimmering and distorting the air about him.

'An illusory field.' He raised the sword. 'A novice spell.'

Earth split and cracked beneath his destructive fury. Stone spikes ripped up from the ground like sizzling, molten-tipped fingers. The air surrounding Izuku shifted.

With a growl, he thrust his leg back and heard air burst from Chisaki's lungs. The hair on the back of his neck raised. A tingle coursed down his spine.

Izuku whipped about, his sword slicing through the air in a horizontal sweep. Oxygen crackled beneath the heat of his flames. Shimmering heat haze leapt back, a multi-voiced chuckle sweeping toward him.

It battered his mind.

'Fast.' Izuku planted his feet and settled into a defensive stance. 'Faster and stronger than I expected. It seems his… blessings are physical more than psychic.'

"You fight like him." Overhaul's daemonic voice boomed through the chamber and in his mind. "So far as I've seen. But you're weak and you will die."

Clawed hands grasped a pistol hanging on his belt. Overhaul brought the weapon to his throat, a savage grin ripping his plague mask.

The trigger pulled back with a resounding click. Chisaki's pupils swallowed the whites of his eyes. Veins bulged, wriggling like black worms beneath his pallid skin. A content sigh streamed from his beak.

"Glory to the Changer of Ways," he whispered.

Overhaul's beetle-black eyes shimmered with foul energies as he slammed his palms to the ground. Insane laughter ripped from his throat and the Earth trembled.

Rock exploded around Izuku in a maelstrom of destruction. It crumbled and reformed at a near-instantaneous rate. Stone spikes and pillars rushed him from all directions.

Izuku twirled, his sword spitting warp flame around him. Looming death crumbled and melted beneath his onslaught.

"You'll need to do better—"

Grey walls shook and crumbled to dust. A black-taloned hand cut through the air toward his chest. Izuku jerked back, his back slamming into stone and cracking it.

White-hot sparks hissed off his sword as he plunged it toward the warp-corrupted man. Flesh tore and sizzled. The sword pierced Overhaul's chest; a gurgling laugh bubbled from his shredded lungs before he began to flicker and dissolve.

The ground rumbled. Stone crumbled at Izuku's feet and a yawning pit opened beneath him.

It swallowed him and he tumbled through the dark. Stone ground stone. Overhaul's demented, melodious laughter echoed in the darkness.

The walls closed in.

Izuku disappeared in a flash of white light and reappeared above the jagged dome.

'He can manipulate the entire room.' Izuku's eyes flitted about the cavern. 'And his illusory powers were better than predicted.'

Shadows roiled in thick miasmatic streams throughout the large space. Overhaul's insane laughter tore from the empyrean mist and rammed his mental shields. They quavered, threatening to buckle beneath the onslaught.

But they held.

Izuku's fingers dug into the sword's hilt. Leather groaned beneath his grasp til blood leaked over the wrappings.

"You've taken Eri from me." Overhaul's hissed words echoed from the miasma. "I'll get her back and offer her to serve the true god of this universe. In the meantime…"

The villain's presence disappeared from all corners of the cavern. Chisaki's laughter faded til all that remained were the noises of dripping water and clattering rock.

Izuku crept through the dark, his senses extending as far as he could manage. Tzeentch's ever-changing, maddening laughter vibrated his skull.

An enraged scream tore through the cavern and he whipped around. Thick, roiling shadows swirled about the dais in a tempest. Raw, animalistic yells and amused laughter pierced Izuku's ears.

His heart dropped in his chest. 'No, you were supposed to leave. Why are you here?'

Izuku's leg muscles twitched, demanding him to charge, but he stayed the desire. He felt Overhaul's watchful eyes on him, a sensation akin to insects scuttling over his skin.

"She was lurking just outside the cavern." Overhaul's beak clacked, echoing throughout the room. "Watching through a hole in the ceiling. It seemed a shame that she wouldn't witness your death and my rise up close. Wouldn't you agree, Emperor?"

"Leave her be, heretic," Izuku hissed. "She has nothing to do with our fight."

Black mist cleared to reveal Mirko's snarling face. Thick rock encased her hands and feet. Overhaul loomed over her, his hand wrapped around her throat. One taloned finger hovered just over her jugular.

"Oh, but she does!" Overhaul's mad cackles pulsed about the room, enhanced by his growing power. "Lord Tzeentch knows all, and you wouldn't allow her to come to harm. She took you in, the only hero willing to do so. She's kept your secrets and you've grown close over the past few weeks. Horus was the Emperor's weakness and she is yours."

Izuku took a step forward and Overhaul's talon twitched down a millimetre. Coming to a halt, a series of low growls rumbled in his chest.

"I wouldn't if I were you," the corrupted villain taunted. "I've grown tired of our game and wish to see this finished now. Throw your blade down behind you."

Steel clattered against stone. White flames guttered out with a dying hiss. Stone wrapped around his hands and feet.

'I can break out if I need to.' Izuku glared at the smirking criminal. 'Play his game for now. Overhaul is falling into my hands.'

"Lower your psychic shields, boy."

The white glow surrounding Izuku's body faded to nothing. He pushed the shield inward and weakened it enough to be beneath Overhaul's notice.

Overhaul pulled a dagger from his belt. It glowed a putrescent purple, humming a sickly-sweet melody. With a wave of his hand, it hovered in the air just in front of her.

"Attempt to break out and you'll die a very painful death." Overhaul jumped down from the dais. "Time to die, Emperor."

Obsidian talons glimmered in the dim light. Overhaul surged forward, a maniacal grin ripping his plague mask. Izuku glared at the villain, a challenge in his eyes.

Time slowed as five obsidian claws pierced his abdomen. Blood flowed in rivers over Chisaki's hand.

"Yes!" Crazed glee swam in the corrupted man's eyes. "For Lord Tzeentch!"

Overhaul activated his quirk and fire scorched Izuku's nerves. Skin tore to ribbons and muscles burst like overfilled balloons. Izuku's innards felt as if they'd been doused in acid.

Black filled his sight as his eyes melted down his cheeks.

A scream ripped from his throat. Overhaul's victorious laughter rang in his ears.

His body withered and was rent to its base components. His very humanity hung by a thread.

'Just a little more!'

And he let go.

"Midoriya!" Mirko's choked scream slammed into him like a train. "No!"

'Don't move!'

His mouth couldn't form the words.

"And so the great Emperor falls."

The sound of a dagger piercing flesh and a feminine yell of pain were the last sounds he heard before his world was consumed in white fire.