More! I... Need... MORE!
Tattered ashen clothes adorn a frail looking teen as he wanders through ruins of civilization. His waist black hair sways to and fro, matted and frayed from years of neglect but still surprisingly strong all the same. His reaches out a hand, blindly scraping along a wall, claws that replace his nails tearing into cement and paint as if they were nothing. The boy grins, jagged and feral teeth a blinding white... Yet hints of pink linger from blood upon his teeth not so long ago. Pale blind eyes stay frozen in place, no use to him but far from being a burden. Beyond the sun bleached skull worn upon his face, he can still 'see' the entire world. He can taste emotions, he can smell colors, he can hear everything around him regardless of it's mobility. Long ago, most people would've been amazed at such abilities blessed upon a human. But, then again, long ago the boy was human. Was.
He hasn't been anything close for years.
"I can... I can TASTE it. All the hate. The pain! Oh, how it's so sweet! So DELICIOUS!" He cackles to himself, a Cheshire grin warping his lifeless face as he does. Vale is so close now, so close he can feel the fear rising within the hearts of the people, and he's delirious with glee. All that negative emotion, all the war and greed, it simply lures him and his family towards it. Beowolves, Creeps, King Taijitu, it was going to be quite a party when they all arrived. They could all feel the invitation like a heartbeat, the heavy vibration of all those beautiful negativities. But he'd decided to make his way alone, letting his family make their own way to the feast as he waltzed from the failures of humanity against the wild. He loved them, he really did, but sometimes he just wanted to be alone with his thoughts. He'd always marveled how easily mankind had collapsed, how quickly innocent lives were sacrificed in the name of progress and 'the greater good'. Grimm were nothing like that, they knew their place in the world and acted purely on instinct. All survival, no rush for power or control. Just existence. They were wondrous creatures, but nobody alive would ever agree to such a statement. To them, they were just violent monsters that sought to destroy everything. He was very much aware of the irony of such thoughts... Till his thoughts were broken by the sounds of humans.
"Halt! Who goes there!?" His eyes darted toward the source of the noise as his claw slipped limp from the wall. Two soldiers, dressed in white plated blue armor, aimed their rifles at him. Pulse based, if he was correct. He hated those rifles, made his skin itch last time he got shot. The two men were steady, clearly fine with what was effectively a suicidal duty, and he could feel their fingers itching to pull the trigger. He simply smirked and shook his head. "Me? Oh, I'm no one important. Just I'd go for a little stroll." He innocently spoke, a talent he'd learnt long ago. If you pretend to be normal, fools will leave their hearts wide open to be ripped out. The soldiers glanced at each other, uncertain of the story, and this simply amused him more. "Sir, this area is highly dangerous and restricted from civilian access. The fact you're out here instead of-" "I don't come from Vale." A instant and cold reply cut off the man. The other took a turn at speaking. "Well, if you're not from Vale, how did you get so far out here? The wilderness is dangerous and you're hardly equipped to just charge through it." The laugh they received sent chills down their spine. Manic, hysterical, laughter for such a stupidly unobservant reply.
"You think I'm unprepared?" The teen growled out, now slowly lurching towards the two men, claws twitching eagerly in anticipation. The soldiers readied their guns, unshaken and ignorant to what lay behind the boy's deathly visage. "I'll show you who's UNPREPARED!" A single shot was fired, but was just as quickly blocked with a swift slash of the teen's arm. There, spread out and interlocked like a shield, was a vast range of Nevermore feathers birthed from his own ghostly flesh. The men gasped in horror as the boy, the Grimm, giggled to himself. He loved this part. With a single flick of his wrist, the feathers fired towards the two grunts before him and forced them apart. As they regained their footing, trying to taking aim in the process he dashed away from their fire. Bolts of blue skimmed past him as he burst from place to place, only a dust cloud to be struck as they fired upon him. They tried to corner him, one firing at him and the other suppressing the area so to force him against a wall, but it wasn't successful in the slightest. Grimm simply dug his claws into the ancient buildings and ran, on all fours, higher and higher as they fired upon him. It was only when he reached the roof that the two men regretted their decision. Grimm kicked off the edge, flipping back on himself, before feathers layered his arms like wings. He burst downwards, propelled toward the soldier who'd suggested he was unprepared, and reached forth with his claws. The feathers turned to ash, but only to replace with claws with razor sharp fangs. Fangs of the Taijitu, no less. The last thing the soldier saw was the gaping maw of a Grimm, formed by the hands of a furious demon. Fangs smashed through his helmet, piercing into his skull and slicing into his eyes like grapes, as he screamed in agony and swung wildly with his arms as his rifle lay forgotten beside him. His friend could do nothing, the distance too great, but watch the young teen slam him into the floor over and over till blood poured from his plating like wine. Within mere seconds his screaming stopped, but Grimm didn't till his head had popped clean from his shoulders. Why?
Well, amidst his final moments, the man had knocked off his skull cap. Grimm didn't like having that knocked off.
'Spitting' out the dead man's head, letting it roll off as the fangs faded from his fingers, he glanced toward the last man standing. The man froze in terror as he looked upon the other's face. There, scarred into the boy's skin, was blood red markings glowing in the darkness. His once dead eyes now shone crimson, pools of gore and rage burning within them. Slowly, Grimm began to walk toward his last victim. His hair clung to his body, slowly merging with him till his torso was nothing more than an endless abyss of black. His arms, legs, face, they all too were swallowed by the expanding darkness. The soldier screamed, firing wildly but simply grew more panicked as his shots had no effect. Grimm flicked his wrist, feathers firing out and impaling the man's ankles to the dead earth beneath him. He screamed and screamed, begged for mercy, but could do nothing as his murderer approached. The teen held out an arm, his flesh warping into the stinger of a Death Stalker, and hovered it over the man's face. Teeth exposed once more, grinning devilishly, was the final horrifying sight for the soldier. The stinger ramming through his skull, popping out the other side with ease, before he was lifted up and dangled like a toy. Grimm took his time, smirking all the while, peeling the corpse of armor before cutting into the skin. He had to keep it clean, avoiding the guts and stomach, but feasted on the dead men like a savage with glee. It's why he'd destroyed their heads, far less meat wasted. He was all but done by the time he decided to search for his skull. It was a little bloody and a little bashed up, but still intact. He licked his lips before placing it back on, quickly cleaning up his arms after. Much like when the skull was knocked off, the blackness that coated his body soon oozed back from his limbs. Within time, it was nothing more than a large length of hair attached to a cannibal.
A cannibal who'd decided to take a doggy-bag of flesh with him.
And so, as he idly suckled on the artery of a heart, he looked out towards Vale. He seemed closer than ever now. Somehow, the 'food' here tasted better knowing that. Taking a bite of his 'candy' (he always saved the best part for last), he began wandering once more as he heard beowolves close in from behind. He waved back to them, swallowing as he did. "Sorry boys! I got peckish. But, I promise you, there's good eatin' if you're heading my way." He grinned as he heard them follow, splitting all but the heart and tossing it to the those who came.
As the Grimm swarmed towards Vale, you could hear the sounds of manic laughter approach from the distance. Broken only by a soft purr of delight as he continued to eat.
"Quickly, this way! This way!" All of Vale was in chaos. First the terrorist attacks, then the Grimm flooding the streets, now both at once!? How had it come to this? To man turning against his fellow man? Was it just greed? Or something deeper? Something with meaning? He didn't know, he just had to try and live through it. As the grey haired man helped others to more secure locations, revolver resting in his hip holster, he froze as he heard an echoing laugh dance through the mayhem surrounding him. As if time itself stopped and only he remain in motion, he couldn't help but stare toward the distant walls of Vale. He swallowed a lump down his throat, hands begging for him to ready his gun.
"No... It can't be..."
Okay, so I wrestled with this idea for a while (mostly cos I suck at action stories) but I'd like to think this turned out well. Just to clarify, Grimm isn't invincible. He's just seriously hard to kill due to excessively high aura levels, though eats tons to help maintain his strength (hence cannibalism his eager cannibalism. The laughter isn't to do with that, he's just insane). The skull he wears doesn't control his 'Grimm-ification' but rather acts like a focus. His resentment and rage is focused on the skull of his dead abuser, which prevents him from Grimming up constantly (as it burns through his aura faster). While not in the story, I did originally want to show he's indecisive toward Faunus due to them being both animal and human. Basically, he wants to kill them but feels like he shouldn't.
As for his abilities:
Fames Serpentis - Hunger Serpent (Serpent's Hunger). His fingers become fang like. While they lack poison and slashing ability, they can pierce through a vast majority of materials.
Ventus umbra - Wind Shadow (Shadow Wind). Feathers form on his arms, allowing a few seconds of gliding. Repeating the action does no grant more glide time.
Tempestatem umbra - Storm Shadow (Shadow Storm). While gliding, Grimm forces himself downwards in a nosedive. The resultant speed makes his attacks stronger due to momentum.
Corruptio - Corruption. Term for 'Grimming up'. Hair disappears, but the body is coated in thick black 'fur' instead. Eyes tint red with spiderweb cracks surrounding. Strength and speed massively increase, but Aura consumption is now 5-10 times faster depending on which and how many abilities are used and how much damage is taken.
The stinger and feathers have no name, though his attack style is called "Fraudulentiis" (Fraud) in respect to his human appearance but Grimm attacks. His weapon is his semblance, which is Mutation (awoken by the substance, or more importantly Dust, abuse he was subjected to over the years).
As for the mysterious person at the end... Well, guess you'll have to wait and see if another RWBY episode inspires another chapter!