Summary: The war is over and the last standing is the supposed Destroy of Time – Allen Walker – the one that lost everything because his friends decided that they would do anything in the war to allow him to destroy the Earl.

After the battle he was left alone in the carnage of the war, the bodies of his friends and family littering the ground as he screamed out his sorrows. He – Allen – gave up walking in the light for he found that he was always drawn – pulled – into the dark.

Instead of fighting the darkness he embraced it with open arms and by doing this he changed, and not just in personality but appearance too.

The Millennium Demon

Chapter 1: Can't I Protect?

Precious little soul, sing out your sorrow

For the time has come and there is no tomorrow

The clock has stopped, never to tick

As the old you disappeared with a click

The faintest of humming was heard throughout the battle field as bloody corpses littered the ground, the person humming stared blankly at the sky, his eyes slowly bled to gold. His ash grey skin slowly bleeding away to a milky white as his black left arm fell limply by his side. His once pure and clean white hair was tainted and stained with the crimson of the people he cut down.

Tears welled in the golden slitted eyes as they slowly ran down his cheeks, the long scar that started from his forehead and ended at his jaw, glowed slightly as blood ran from his left and tears from his right. For his left was cursed and could not cry normal tears, so he cried blood.

He cried for all the lost souls.

All of his friends.

All of the people he called family.

The figure's humming stopped as he let out a cry of pure sorrow, if any human had heard it they would have had their heart break and shatter into a million pieces or lost all of their sanity. This man – Allen Walker – was the only survive of the Holy War for his friends had sacrificed everything to make sure he took out the Millennium Earl, which he did but at the cost of losing all he loved.

Throughout his life he had always lost the ones he loved most or cared about. God seem to enjoy watching him suffer for all he has are so many bad memories that they nearly make all the good seem nothing but a lucid dream. A dream that a pleading boy wished to have for he had hope – even if were only a little – that things would turn around and go his way.

But God seemed to have other plans.

The boy - Allen – seemed to be surrounded in shadows for all that was left was the dark in him. He had given up on the light for he has seen there is none, after everything he been through.

Allen looked around the battle field as a golden golem wiggled its way out of a dead Lenalee's hand for she has jumped in front of an attack to save Tim and me. It ended up with her being impaled with the Earl's sword, such a tragic death but they all were.

All of them.

He tore his eyes away from the carnage as he looked at the sky, a grin working its way onto his lips as he closed his eyes and let out a laugh. The laugh was biter and humours as he raised his right hand, clicking his fingers together as his outfit changed and all the blood and dirt vanished off his form.

He now wore a green and white stripped dress shirt with a red tie, a cream coloured long coat, black pants and a top hat that had white piano keys going around the brim. He wore black dress shoes as his hair was held back with a red ribbon. Timcampy – a golden sphere that was round and sprouted wings, short legs and horns with a pale yellow cross that split in half when he smiled or revealed his teeth – nuzzled his master's neck in a comforting manner.

"I'm must keep walking and walk in the dark for the light doesn't seem to want me." Allen looked at Tim as his aura shifted and his appearance changed as a dark whispered in the back of his mind kept telling him to follow the path set in front of him.

Allen grinned as he followed the voice that told him were to go, the only words that the whisper kept saying was demonic and welcoming.

'CoMe aNd LeaVe THe LiGHT. TuRN YouR BaCK oN THiS WoRLD aNd CoMe To MiNe, FoR i PRoMiSe THaT You'LL NeVer HaVe To SaY GooDBYe aND You MaY Do aS You PLeaSe aS LoNG aS You STaY ouT oF THe WaY oF MY PLaNS.'

Allen nodded to the voice as a portal appeared in front of him, welcoming him to the world of Gehenna.

One hundred and forty years seemed to pass as a boy – well what appeared to be a boy to most humans – sat in a park under a blossoming tree as he stared at the darkening sky, his golden eyes fixed to it. It had been over a hundred years since he had been in the human world and for about forty years he wondered the world.

The shuffling of footsteps alerted him to someone as his golden tail – that looked very similar to his small companion's – slowly curled around his stomach, his top hat hiding the small golden horns. His golden eyes looked at the source of footsteps to see a teen sitting on the swings; he stared at the ground seeming depressed about something.

Even though he – Allen – had left the light it didn't mean he had lost his manner or polite behaviour. He slowly stood and moved over to the teen, placing a hand on his shoulder as he grumbled out. "Yukio, I know you came to bring me ho-"

He stopped speaking once he saw that it wasn't his brother, he narrowed his blue eyes at Allen slightly as he looked away. "My bad… I thought you were my brother."

"It's alright young prince." Allen said while releasing the teens shoulder and bowing slightly, he could tell that Satan's powers dwelled in the boy but had yet to full awaken, but it didn't mean that Allen couldn't sense his Lord's power.

Said young prince looked at me weirdly as he was about to get up when Timcampy decided to curl up around his arm and hold him to the swing. The boy cursed as Allen grinned inhumanly wide, his golden gaze shifted to Tim as the boy tried to pull his arm free. Allen chuckled as he shook his head, moving away from his young prince as he looked at him, his voice was soft and melodious. "Tim, release him. We wouldn't want to upset Him."

He pulled his gaze away from Tim as he unwrapped from the boy's arm; he inclined his head as he tipped his top hat to him. "I'm Allen and that is Tim, he's my protective partner. I'm sorry if he cause you harm, boy."

The boy stared at me for a moment before slowly nodding his head; the boy could tell there was something not right with the man in front of him. The boy muttered out a quiet 'whatever' before standing and quickly turning on his heel and walking out of the park, Yukio – a boy with pale skin and two moles under his eye and one near his chin – appeared around the corner as the boy – Rin – walked past him, pulling on his arm. Mumbling a 'let's go home' before heading back to the church.

Allen stared after the boy as a wide grin spread across his face; he spoke to his companion as he followed the two boys. "Tim, I think we just found an interesting target. I wonder what the Lord has planned for his sons."

With that Allen followed the twins to a church, Allen could sense the weak barriers around it but decided to wait and watch for a little while. So here he sat on a roof across the church looking down upon it and waiting to see what happened.


The next day whiling watching the church, a persist walked out of the church; he looked around the area as he swatted the Coal Tars out of his view. He looked up into the sky as he sighed, breathing in the fresh air before grabbing out a smoke and lightening it.

He looked around his surroundings before his gaze landed on me; I gave a grin and waved at him from on the top floor of building. Timcampy hid behind me as I jumped from the roof and disappeared into the crowd before I appeared next to the gate of the church, grinning at him. "Hello Shiro Fujimoto. What a charming morning it is, isn't it?"

I looked out the corner of my eye as I looked at him; he now stood next to the gate as he narrowed his eyes at me. "Indeed it is. What are you doing here?"

"I'm just looking around; it's been nearly over forty years since I've been here and nothing much has changed. Also, I mean you no harm Shiro or the other priests," I clicked my fingers as my outfit changed to black hood that cover my white hair and horns, white short sleeve shirt, grey skinny jeans with black combat boots and a pair of dark grey gloves. Silver hoops and a long golden earing in my ears as I turned so I was facing him and a small smile was formed on my lips, "I simply just want to watch the two boys you have under your care. I know they are the sons of Satan and only 'one' inherited the genes but I just want to look after them for a bit. You have my word that no harm shall come to them by my hands."

I bowed slightly as my grin threatened to widen, he's going to believe what I'm saying for I can tell. I wiped the grin from my face as I waited for his answer, which I got shortly after he stood there in thought. "What makes me think that I can trust you demon?'

"I've never broken my promise until either one of us die. The last person I said that I would protect died trying to save me and after I destroyed the person who hurt them, I buried each of their bodies. It took me a week to burry so many bodies but they were once my family. But that was many years ago and I kept my promise, like I'm still doing know." I smiled slightly in the memories of all my friends before I shook my head, and reached up to gently touch the golden earing that hung from my ear.

'Keep walking, till the day you die.'

Mana's words echoed in my head as I looked into the eyes of the priest, they held something that I couldn't decipher. "If I agree I'll get someone to keep an eye on you and don't show any of your extra appendages to anyone other than me, understood?"

"Understood, Shiro." I inclined my head as I forced my way through the barrier, slight pain flared on my skin but it was nothing compare to what I've felt before, I stood in front of Shiro with a slightly slouched position as steam came off my figure.

"But before I introduce you to the others I want to ask someone about you. So, come with me." Shiro wondered off to a door were he put a key in the door and twisted it, he opened the door to an office and sitting at the desk in the office was none other than Mephisto.

I groaned slightly as I looked at him, I could already tell I'm going to regret doing this. "Oh, Shiro it's been a while, how are things fairing on you looking after the kids?"

"Its fine and I came to you about him." Shiro jerked his thumb at me as Mephisto ran his eyes over me before his eyes flashed in acknowledgment.

"Why if it isn't Satan's little pet, Allen Walker." Mephisto smirked at me as I growled at him slightly, crossing my arms as I removed my hood.

"Hello Mephisto, you haven't changed and I'm not his pet." I hissed at him as he merely laughed at me and went back to playing with a pen; he dropped it and held his hands together.

"So, what are you doing pet?" Mephisto's grinned as he lent forward on his desk, his hands blocking the view of his mouth as he narrowed his eyes.

"I wanted to watch over the twins of Satan. Protected them," Mephisto raised a brow at this, as if asking why would I of all people want to, "I need to do something and I've found something that spikes my interest."

Mephisto hummed and gave a quick glance towards Shiro before his eyes landed on me again. He removed his hands from in front of his face and slouched into his chair, throwing his arms in the air as he shrugged. "I see no harm in you watching them but beware, pet. You are in dangerous grounds so watch your step, understood?"

I grinned at Mephisto; it held no kindness or warmth it held only a mockery as I bent my back slightly in a bow. "Understood, dog."


I sat on one of the beams in the church looking down as Rin and Shiro slammed open the door and moved to the front of the church, pushing the alter to the side as it revealed stairs going down. I raised a brow as I quickly stood and jumped to the furthest beam to the door. The entrance caving in as a truck smashed its way through the front of the church.

Narrowing my eyes as I crouched on the beam, my gaze glued to the person stepping out of the truck and to my surprise it was Astaroth, King of Rot. I watched as I narrowed my eyes at him, them flashing a murderous gold. He had goat-like spiral horns, long sharp nails, and canine like teeth, red eyes, a Demon tail, and a long tongue that flicked out for a second. He grinned at the priests as they prepared to fight the demon king and all his little demons. Demonic Mushrooms and Ghouls appeared in the church as my tail uncurled from around my stomach, it sliding out of the hoodie and swaying behind me. I growled as I readied to pounce on Astaroth, I jumped from the beam and over to Astaroth who looked at me with surprise. "What are you doing here lil' pet?"

"Why do all the Kings refer to me as that," I grumbled out as I stood a couple paces from him as I let my golden tail swing calmly as I looked at him in the eyes as the other priest fought the other ghouls and demons, "I'm protecting the Sons of Satan, Goat~!"

I grinned inhumanly wide as I tilted my head to the side, Astaroth narrowed his eyes as his body shifted and he slowly grew taller and his appearance changed until he was in his full form, letting out a monstrous roar. "I'm going to enjoy this lil' pet~ I hope you've been training."

I let a laugh leave my lips as I step to the side, barely missing Astaroth's fist that came into contact with the ground, cracking it. "Don't worry, I have been Goat~!"

I dodge all of the attacks he sent me as the priest struggled to keep the multiplying ghouls and demons at bay. I narrowed my eyes slightly as I ran over to the priest and knocked away or destroyed the demons that were attacking them, grinning widely as I did so.

Astaroth took this as an opportunity to go for Shiro who was shooting demons with his shot gun without a care in the world. His eyes were narrowed as he looked at Astaroth, who was laughing happily to himself as I jumped in front of Shiro when Astaroth swiped at him. I was flung into the wall as I gasped in pain, spitting out a small amount of blood as I pushed myself off the ground shakily.

"I told you before… You're not getting to him Astaroth!" I pushed off the floor and ran at him, growling as a silver glowing halo appeared above my head as I pushed Astaroth to the ground, holding him there as Shiro banished him from the boy's body.

The boy's body reverted back to normal as I huffed and slowly stood as Rin somehow managed to get out from under the alter. He stared wide eyed at me as I pushed back my demonic powers until the halo above my head shifted back to my hooped earrings. I looked around the destroyed church, growling as I walk out of the building and searched the area to make sure no other demons where going get near the church.

My slitted eyes looked around the dark area as I hunched over grabbing at my jaw and clawing at it. 'No, I can't lose control. I can't lose control. Can't let them see that side of me. Don't let them see, don't let them see.'

I ripped away the skin of my jaw as it slowly started to repair the damage I had caused. I shakily breathed as laughter that sounder all too familiar was heard from inside the church; I ran to back into the church only to freeze in place and stared wide eyed at Shiro. No, not Shiro but the blue flames and bleeding eyes, mouth and nose, my breath caught in my throat Satan looked over at me with a wide grin. "AH, iF iT iSN'T MY LiTTLe MiLLeNNuiM DeMoN~!"

My body shook slightly as Rin just gasped and looked at me as my tail fell between my legs like a scared dog. "L-lord Satan…."

"HaHa! NoW, MY SoN LeT uS ReTuRN To GeHeNNa!" Shiro – Satan – grabbed his wrist as he pulled on and dug his nails into it, drawing blood as he summoned a Gehenna gate. The gate slowly formed as my legs gave in and I fell to the ground, watching as Satan threw Rin into the gate. I raised a hand, wanting to save him but not being able to defy Satan.

'Why can't I help him? Why can't I move? Am I really that useless that I can't even protect him from his biological father? I couldn't even protect my friends. I couldn't protect my once living family. I can't protect anyone.'

My hand fell to my side as I stared blankly at the rubble on the ground, my mind swirling with thoughts as Rin screamed out for someone to help him and yet I couldn't do anything as my head was haunted with the thought of not being able to protect and save.

"Why can't I protect anyone, Neah?"

Hello My Lovely Readers~!

Another D-Gray Man/Blue Exorcist Crossover! I had fun writing this cause I actually wrote this one before my other but I found it easier writing my other one. I hope you liked the chapter and I can't wait to start writing the next chapter... Which I am gonna do now~

Oh, yeah and this story may be updated every couple months or weeks... Dunno...


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KillerAkuma Destroying Here Way Outer Here~