Crimson Shadow

A whisper in the air.
A rustle in the leaves.
The Crimson Shadow comes for blood.
He moves with a purpose and never has a doubt.
As to which mortal he is to slay.

Geriad looked up from his books as he heard a rustle. Seeing nothing, he dismissed it as a gust of wind and turned back to his tomes.
In the corner of his eye he spied a dark blob moving through the window.
He shot upright, his eyes filling with terror as the immaterial form solidified into something from his worst nightmares. He tried to scream but all that came out was a squeak of pure fright. The avatar of death grinned maniacally and descended upon the stricken scholar.
He knocked his chair over and scrabbled at the wall. A hand gripped his head and he shrieked, his flesh sloughing from his bones as the life was sucked from him. A dark scythe howled towards his head and he experienced a moment of pure horror as the blade severed his head from his body.
Drinking in the energy that leaked from the ravaged body, the dark form turned and glided away, dissolving into the air.

There's the first part. Feel free to add to the story if you wish.

The night seemed to drag alone for the crimson creature. The scholars and priests of his cult worked tirelessly into the night as he himself just gazed into the night. perched on the grinning features of a stone gargoyle. He could feel himself drifting into his subconscious, ready to fall asleep. As his head bowed dark strands of ebony hair fell about his face, acting like a curtain to his crimson hues.

A sharp intake of breath suddenly awoke the creature from his slumber. His nostrils flared as they detected the faint wave of a powerful aura. His eyes slowly opened to the night as long, slender fingers cracked with anticipation. Anything that dared trespass into his realm would pay dearly for their stupidity.

A muffled scream came from within the hallowed stone walls of the creatures church. His pale face contorted with rage, and with that the creatures form dissolved into the darkness. It was time to meet the fool.

Kratos slid through the alleyway, his breathing controlled as he though of the creature he was here to destroy. His sword hummed gently, sensing his disquiet. He had memorised his spells before he came, so that he would not have to chant the whole mantra when the fight came. He wondered if he would live through this fight.

He stopped as he scented a foul reek. The creatures nest had to be close. His eagerness rising, he dashed in the direction of the noxious smell.
***
The immaterial smoke watched the man with cold yellow eyes. The mortal dared to violate his home? He would pay the ultimate price for his stupidity. But, it thought, he had bravery. Not many would venture into the lair of the creature feared in all dimensions. Pondering this, and what his motive could be, the ghastly form glided after the human. He may yet prove useful.
***

He had reached it's nest. It was nowhere to be seen. A sudden dread filled his heart:it knew he was here. Reacting with unparalled speed he spun, glowing cyan sword pointed directly at the abomination slithering towards him. His sword quivered in his hand as he spoke the word of power that summoned his guardian. A pinprick of light formed by him; suddenly coalescing into a tall blue form not unlike the creature. It shivered and morphed into a human form. A huge hammer appeared in it's hand; a glowing aegis of light forming a perfect circle in the other.
"Your will?"
" Destroy this thing!" he shouted. It nodded and shot through the air towards the thing. It did not move, apart from it's inky darkness writhing a bit. When the giant spectral form was about to smash it into pieces with the hammer, something happened. The figure froze and, a second later seemed to shatter into pieces. Kratos backed up against the wall horrified at the defeat of his guardian ghost.
The shadow grinned, taking a remotely human form, and stepped towards him.

10 minutes later.
Kratos cursed himself for not being as careful as he was bound with dark chains of iron to a wall in the things lair. Before long his captor came to him. It took on a human appearance so as to speak with him. A melancholy voice seemed to come from everywhere and yet nowhere at the same time.
"Why do you trespass in my realm? What harm have I done to you?"
"You burned my village, fiend."
"Which one? There are so many I have torched over the years."
"You know damn well which one." Kratos growled, seething with anger; he knew it was playing with him, and it knew it too.
"Ah yes... Tarnus... A most annoying thorn."
"IT WAS MY HOME!" He roared.
"Why do you shout? I am merely making conversation. And I came here to make you an offer, not to be insulted."
Kratos felt a glimmer of hope in his heart. He may have a way out.
"Which is?" He asked nervously.
"Join me in my dominion, become my apprentice, my student, for even one as I cannot live forever."
"What in hell makes you think I would join the likes of you?"
"We are alike. Your destiny and mine are tied. And no-one else would be so brave as to venture into my palace without anything more than faith and a meagre spirit."
It waved a hand lazily and then chains holding Kratos unraveled in tendrils of darkness.
His sword was on the ground in front of him and as he locked eyes with the beast he saw the only course of action available to him.

He leapt forward, snatching up his sword as he did so.
"Burn in hell, devil spawn!" Kratos yelled.
The warrior soul within the sword roared to life, the bright aura around the cyan blade becoming almost incandescent. The deathly shadow hissed, the sound echoing round the cell, like a thousand snakes all hissing in tandem. Muttering a quick spell, Kratos's was set ablaze, streaming with white fire. If the sword had been powerful before, it was most certainly a deadly tool now. Dashing forward, he swung with a vengeance that had not burned so brightly since his home was immolated. However, his sword met only air, as the beast had already vanished, reappearing with a writhing of smoky tendrils at the other end of the room.
Quite out of nowhere, a silver blur shot through the air, almost too fast for the eye to follow. The creature only just saw it coming, for it jumped to the side at the last second, narowly avoiding the dart. There was a pause, then a flurry of shots pounded the creature. Shrieking in pain, it dissolved into the shadows, seeking to nurse it's wounds. Kratos stood still for a moment, wondering what the hell just happened.