Izuku gritted his teeth, the repugnant smell of a demon… No, not just any demon,
Lullaby, the demon of mass murder music magic, filling the car. Spreading his arms apart, hands thrown wide, he created two waves of water and slammed them into the dark haired man, clenching his fists together and forming the waves into a sphere holding the man, "Water Devil's Prison!"
Let's see him get out of that.
The man fired a spike of his shadow at Izuku, who gritted his teeth and prepared for impalement... Only for an ice wall to appear and catch the spike, "Thanks, Gray!"
"Anytime, buddy!" Gray responded, running across the gap and slapping his hand against the purple water, freezing it solid. Izuku let go of his grip on the water, content that the man, and Lullaby, were frozen solid.
Which was why Izuku was so startled when Erza cried a warning and Izuku turned just in time to dodge a dagger of shadow from the man halfway submerged in shadow. Shit!
Erza brought her sword down in a two handed executioner slice, only for the man to slip into his shadow and out the window. No, he didn't, not on Izuku's watch!
Izuku kicked open the wall of the train, running past the evacuating crowd. He could hide in the shadows, but he couldn't hide Lullaby's scent. He had to kill it before it woke up. Izuku felt the demonization marks spread further than he had ever allowed them to before, covering his entire face, horns starting to grow from his forehead.
The man rose from the shadows, firing lances of them at Izuku, who charged through, uncaring that his UA uniform got torn in the charge. He grabbed the man by the throat before he had time to react, reaching to tear Lullaby from his hip, only for a dark voice to say,
"That's enough. I will not die so easily."
And then, the flute began to grow, swallowing the man and forcing Izuku back as it grew into a mountain sized beast, seemingly made of wood, with three pink glowing eyes. It hadn't been dormant, Izuku realized as he allowed the demonization process to swallow him completely.
It had been waiting.
—
Lucy ran up alongside the others, stopping as they found a winged, demonic rabbit like creature flying around the giant monster, releasing huge blasts of purple water at the creature.
"You don't think…" Gray started, only to trail off.
"Demonization? It looks like it," Erza said.
"Demonization?" Lucy asked.
"People who use Devil Slayer magic like Izuku eventually get Demon Genes mixed in with their human ones. By letting those genes take control, they can take the form of a demon. It's a dangerous technique, so Izuku doesn't use it lightly. Come on, we have to help him."
Erza flashed with light, before appearing in a set of armor that looked like what a winged templar would wear. Swords began to appear around her, while Natsu breathed out a torrent of fire and Gray called up to Izuku, "Unison time, buddy!"
Water began to circle around Izuku's overly long arm, turning into a giant drill as he landed on the ground. Gray planted his hand on Izuku's back, the drill freezing over as their magical energy spiked. Erza cried out "Now!" And everyone other than Lucy, who had been watching in awe, launched into motion.
Erza took off into the air holding a sword, the others following in her wake. Dodging a sweep from Lullaby's arm, she drove the sword in her hand into its head, the others peppering its body and all of them leaving small ghostly blue flames rising from them, "None Shall Escape My Grasp, None Shall Escape My Sight! Natsu!"
"With Flames In My Right Hand, And Flames In My Left Hand! Put Them Together And This Is What You Get! FIRE DRAGON'S BRILLIANT FLAME!"
Izuku took off, apparently not slowed an inch by the huge chunk of ice on his arm, and waved the other, washing away the red flames burning away Lullaby's face, only to leave the same ghostly flames burning from it. Lullaby let out a pitiful, especially for a demon, wheezing noise before Izuku drove the drill into the demon's face, "Devil Slayer's Frozen Drill!"
The drill began to spin around his arm, tearing chunks off Lullaby's face, until the water inside grew more forceful than the ice on the outside could take and it shattered in an explosion of ice and water that blew Lullaby's head off completely.
Izuku landed, sharing a side fist bump as the pitch black on his skin receded along with the wings and ear-like spikes of hair. Running a hand through his messy hair, not that it did anything notable to Lucy's eyes. In front of them, Lullaby shrank down to it's original form as a flute and Izuku picked it up, staring down at the three eyes… Before coating his hand in water and crushing it, the remains burning with the ghostly flames until nothing was left, "And now another charm is o'erthrown. Come on, we still need to find out why Esienwald wanted Lullaby."
