Author Notes: First time writing a crossover fic and it features a crack pairing hahaha! I really think Sebastian's real name is Malphas, so I've stuck with that here. Seeing as Malphas is a prince and great president, I though I'd give Neuro a title too and 'marquis' sounded right enough since it ranks just below a prince in ranking of nobility. People need to recognize NeuroxSebastian more quickly – DEMON POWER FTW.

Can this be categorized as yaoi? Hmmm… First time writing it lol. But it never felt like yaoi to me…

Disclaimer: I don't own Majin Tantei Nougami Neuro and Kuroshitsuji or anything related to them.

A tall demon with the face of a purple bird that bore the resemblance of both toucan and parrot with a large yellow beak accompanied with startling emerald eyes advanced down the large empty hallways of a luxuriously constructed palace with confidence. A pair of twisted horns sprouted from the back of his head, his ears covered in a patch of dark brown fur although he had golden blonde hair with small triangular hairclips clinging to the ends of each strand. As he marched on, the soft clicking of his brown boots against the tiled floor resounded hollowly against the marble that surrounded him. The demon was formally dressed for the occasion, adorning a white scarf tied like an ascot cravat which was tucked into a shocking blue vest and a pair of trousers mostly covered up by the white hemmed coattail that extended from the vest to his ankles whilst a black stretch of silk with faint golden embroidery falls down the front of his clothes from beneath his vest. Above all this was a hefty high collared coat the hue of midnight that trailed a little behind him; the insides of the coat a brilliant scarlet, the sleeves and hems threaded with threads the colour of dark chocolate as a golden belt snaked itself around his waist. Snow white fur wrapped itself around the high collars of the coat which reached well past his hidden ears, two dark green jades framed by gold attaching a crimson cape at the back to his coat.

Taking a sharp turn, the bird faced demon found himself face to face with a door far too familiar for his tastes. This was no ordinary place to be in even amongst all the grand structures of Hell – this was the palace of Malphas, otherwise known as a Great President and a Prince of Hell who has forty legions of demons under his command. Knocking crisply at the door, the mystery eating demon awaited a reply from the expected occupant inside until he pushed open the door and stepped into the room. The large room was just as equally dull as the rest of the palace, a place entirely devoid of colours of any sort, consisting only of shades as befitting of the demon prince that appears in the image of a raven. Seemingly following the prince's latest fascination with what the humans called 'Victorian styled' items, the room itself was styled in that manner too, sporting a dangling crystal chandelier from the ceiling and various other things. The marquis was relieved to an extent to see that the prince did not choose to dress in human clothing. The great president wore clothing somewhat similar to Neuro's but was more elaborate and did not show a single hint of colour apart from the garnets that were found on the president's belt and cape along with two smaller sapphires and the golden bordering of some of his clothes. Even the elaborate embroidery was done in black thread, only seen when the sunlight reflected off it. And despite not being short by demon standards, the president wore knee high heeled leather boots to promote his height even more.

"Marquis Neuro, how long has it been?" The figure standing by the large window on the other side of the room inquired in his husky voice.

Neuro bowed in respect and noticed the game of chess that was set out on the table in the middle of the room, a game humans enjoyed playing, "It has been a month, Your Royal Highness."

With a graceful swing of his cape, Malphas turned around and sat himself at the table where the chess was laid out with his long legs crossed, "And how long by human measurements?"

"A year, Your Royal Highness." Came the reply.

The demon that took delight in ingesting souls hummed contently, "I've been waiting for you to return – none of the demons down here have the intelligence to win against me. Also, you can drop the formalities since we're alone in here."

The marquis settled in the armchair across from the prince, giving the great president a look of peculiarity. "Then pardon me by asking why you look like one of those ignorant fools who live in the surface world."

True enough; Malphas' skin was pale unlike his normal dark grayish tone and the black hair that framed his face shorter than usual, even though his teeth remained razor sharp and his eyes were still their dangerous crimson hue. He didn't even bother wearing gloves to cover his hand with claw like black nails. The raven demon paused in his rearranging of his glinting chess pieces and leaned back into his armchair, his blood red slitted pupils boring back at his guest. "I've become quite interested in human expressions lately. So I would like it if you covered up your big beak with a human face." The monochrome clad demon used a gloved finger and drew an imaginary circle in the air around Neuro's beak.

When the purple bird head vanished and was replaced with human features, Malphas smiled falsely at his companion, resuming his rearrangement of his chess pieces. The pieces were made of metal, Malphas' pieces a dashing silver and Neuro's a dull bronze like tint. Each piece was ornately and carefully carved with skill, detailed complex patterns etched in the pieces. The chess board itself was a shiny sheet of metal, lifted above the table top with elaborate elegant curves of metal.

"You do know that it's practically impossible for anyone to actually beat you at this pathetic strategy game right?" The multi coloured hair demon stated matter-of-factly, letting his chin rest on his palm as he lazily moved each piece into place with his other hand.

The Great President of Hell was well known for his history with human interactions, accepting any offerings made to him and possessed a grand knowledge regarding humans and their odd cultures. The prince chuckled, a gentle rumble in his chest, "I would think you had the chance, Neuro. I do care about your general wellbeing as a fellow bird demon since I doubt you actually have to use your intelligent parrot brain for much up on the surface." The black haired demon raised a finger and pointed to a pawn in the fourth row from the right as he seemingly pushed it forward two steps with air.

"Ravens, crows and magpies have the largest hyperstriatums and brains amongst birds with larger number of brain cells." The marquis calmly said as he pointed at the pawn also in that position with his middle finger and flicked the air so it moved forward one step.

Malphas blinked slowly and moved the pawn in the column beside his first one forward two steps again. "The brain-to-body size ratio of parrots is actually comparable to that of higher primates."

"So are ravens." A black knight leaps onto the front lines.

Before saying the next phrase, the red eyed demon snickered a little. "Parrots are highly skilled at using tools and solving puzzles." A silver knight joins the fray, albeit being held back one step behind the pawns.

Neuro raised an eyebrow and shot the demon a glare. "Ravens are able to exhibit a complex decision making ability and have rich awareness in surroundings." He placed unnecessary stress on the word 'complex'. Another pawn moved with a wave of a finger.

"Parrots display a high learning ability and are able to use words to identify objects, describe them, count them and answer difficult questions in the human language." A bishop flew over the wall of pieces, prepared for battle behind one of the pawns.

The bishop in the opponent's army filled in one of the dark pawn's space. "Ravens have the innate ability to cogitate object numbers."

Letting his scarlet eyes sweep over the chess board, Malphas let his queen take a step forward without a second thought. "Parrots are well known for their ability to imitate speech and other bird sounds."

Another pawn made its move. "Raven intelligence is evident by their mastery and manipulative powers over other creatures in their domain."

Hence the calm bickering continued, argument and facts delivered one after the other as the game proceeded. At one point, the entire chess board was in complete disorder; both armies had lost the equal amount of pieces whilst pieces were scattered everywhere on the board, the original neat lineup of pieces completely broken. As the finish of the game neared to an end with the disappearance of three more pieces on both sides, the two crowns of black and white were finally within distance as the black king took a step forward towards the enemy. From appearances only, the white king was doomed with no escape, an opposing crook ready to attack any second. But upon more detailed analyzing, one would realize that the queen of the white army was right behind the black king, also ready to strike the final blow.

Picking up this vital clue with a flicker of his deep green eyes with a demonic flair before Neuro made a lethal mistake, the mystery consuming demon shifted his king to the side, protected by his queen and a pawn. The marquis despised losing with a passion and yet even he, the demon who solved all of Hell's mysteries, will have to show at least a shred of respect to a Great President and Prince of Hell who was superior in both strength and intelligence.

"Oh?" Red eyes settled on emerald for a moment as a smirk spread across Malphas' face. He urged the pawn that had been diagonal to the king forward to meet with the opposition's queen.

The marquis drearily twirling a strand of hair from his dark brown bangs used his other middle finger and pushed his dark queen forward and replaced the pawn as the silver metallic piece dissipated into dust. After he made his move, it was only then that the parrot demon realized his dire mistake. Or rather, he had repeated his mistake. Neuro's lips drew a tight line as the prince purred merrily, shoving his quickly forgotten queen behind the dull king and destroying the pawn on the way, the enemy's queen unable to return to her husband's side in time. But snapping back to attention, Neuro gathered his plans together again as he moved his king away from the silver queen, backing against the edge of the board.

Sliding his only remaining crook along so that it was aligned with the black king, Malphas asked, his hoarse voice heavy with arrogance, "Now what, parrot? Seems like a checkmate to me."

The multi coloured haired demon sat up in his arm chair, his spidery fingers tips tapping rhythmically against each other. "As expected of 'Sebastian'; indeed exceptional by reason of age. Have I ever told you that I'm really glad you don't eat mysteries?"

"Maybe you're just not using you entire brain," The demon known as Sebastian at one point in time reached forward this time and tipped the green eyed demon's king over, "I know your capabilities well enough, Neuro; no point in deceiving me."

Raising a hand enfolded in a black glove as if he was holding something invisible, the emerald eyed marquis of the demon court blinked as a parrot with impressive plumage of a billion shades of purple and blue perched on his hand in a flurry of its flapping wings. Inspecting the creature with sham curiosity, the multi coloured haired demon gave the parrot a gentle fling, prompting the animal to fly off and rest on Sebastian's shoulder.

"Consider it a gift to offer my apologies for being rude." Neuro's lips curved in an innocent smile.

"Then I believe a gift of gratitude for coming to accompany me is in order." He replied. Stretching a hand out, the great president let his stretched out fingers curl back into a loose fist one by one like a wave rolling into the beaches. A small invisible curtain seemed to be swept aside in the air as a large black bird swooped down and landed with grace on Neuro's open hand, its sharp talons digging into his palm. The raven looked spellbound for a while as it peered into the parrot demon's green eyes with fascination. The marquis used his middle finger and jabbed the bird roughly, making it let out a deafening squawk.

A grin of sadistic glee stretched across Neuro's face, revealing rows of sharp teeth, a flicker of interest burning in his eyes. However, with a snap of the Prince of Hell's fingers, both creatures disappeared in a curtain of cascading feathers.

"Now that we're done with appetizers and greetings, how about we move onto the main dish for today, Neuro," Sebastian's demonic blood red pupils gave a shuddering pulse as he stood from his seat, temporarily blocking out part of the sunlight cast into the room by Hell's sun outside, "I'm sure a bird with intelligence like your's would know what's next on the menu."

The marquis remained seated in his armchair, the infinite pit of his mysterious dark green eyes showing a look of mild inquisitiveness.

"I thought there was a miniscule mystery attached to your invitation; do you think I can devour it now that it's on the tip of my tongue, Your Royal Highness?"