Note: I don't intend to make Avenger overpowered or something like that, he just happens to have much more prana/mana than usual so his stats increase 3 times.

Warning again, beware of spoilers for Fate/Hollow Ataraxia and this fic also contains 'Tales of' elements.

*Note*: Re-uploaded to announce an important note in the end of this chapter.

~Chapter 1~

They called him the most wicked being ever existed, the Embodiment of All Evils in the world, the God of Evil. Rias once believed so, until she found an old book in her house's library. It still depicted him as Ahriman, God of Darkness and Evil, but she soon changed her view of him after reading his backstory. Thus she became one of the few persons in the world actually sympathized Angra Mainyu.

It was a normal day like ever. Her brother gone to his work, her parents busy with their businesses, leaving her with the maids and butlers. The night soon came, and she was alone in her room, re-reading the book about Angra Mainyu again.

'I wonder if I can meet him and show him that not everybody hates him'

The young Rias thought innocently without realizing that, she would soon meet Angra Mainyu in a circumstance that could not be any weirder. Finishing reading the book, Rias headed to the library to take another one, something could kill her boredom and loneliness. She then found an equally old book, no, diary to be exact, to the book about Angra Mainyu. It contained the ritual of summoning a familiar, one of seven knights that would become your guardian.

'Huh, odd ritual. I wonder if Onii-sama knows about this'

As she read it, Rias heard a scream from outside. It came from the main hall. Rias closed the diary and rushed to see what happened.

Before her were the corpses of the maids and guards of her family. There was a group of armed Devils talking to each other, their weapons stained with blood. Rias attempted to run, but fell instead. Hearing the loud *thud* above, the Devils turned around and saw her. One of them smirked and said aloud.

"Looks like we don't have to split and search. The little brat is coming right to our grasps! Get her!"

Rias didn't need to hear twice as she used all her strength to run to the library and locked the door. But it only stalled a little time as they broke the door down. Rias tried to unleash her family's Power of Destruction but due to her inexperience with it, the blast only sent them back a few meters. The Devil earlier quickly recovered and jumped at her, kicking her and yanking her hairs violently.

"Oooh so powerful, aren't we? Well, not anymore!"

Rias was hurt a lot. She was basically tortured by that Devil, being punched, kicked and slapped rapidly. Just as she thought her life was over, Rias saw the old diary on the ground. She weakly reached it and opened it at the page instructing how to perform the ritual. Luckily, only chanting required. Rias started speaking the incantations in her head, knowing that saying aloud would be suicide.

'…..From the Depth of World, attended by numerous great words of power. Come forth, O' Great God of Darkness, All The World's Evil, my Guardian Knight, MY SERVANT!'

In seconds, everything in the room was blown away by a strong gale. On the ground, a magic circle with unfamiliar symbols appeared. From it, a black individual emerged.

"Oiya, the weakest Heroic Spirit is here! Servant Avenger, at your service!" The 'creature' spoke with a playful voice. As it said, the black aura soon faded and revealed a young man with dark skin and many glyphs tattoos, black hair with a red headband and a red worn pants. If she had not studied about him prior to this day, Rias would have mistaken him to a normal young man. But indeed, Angra Mainyu was a good-hearted young man that was selected to bear All the World's Evils inside him so that the people could 'live in peace' as the book described.

"A-Angra Mainyu, sir?" Rias timidly spoke, prompting him to turn at her with a curious look. It seemed that this little girl had summoned him. A smile grew on his face.

"It appears that you are my Master, aren't you kid? If so," He bowed before Rias, who got surprised at his action. "I, Servant Avenger, will gladly serve you and shall lead you to victory – "

Avenger heard noises from the door to his left. A bunch of unfamiliar soldiers burst into the room and pointed their weapons at him and the girl. He raised an eyebrow when she yelped and hid behind him as Avenger turned to the intruders. He grabbed a broken piece of metal nearby and injected it with his corrupting aura, turning it into a makeshift blade of sort. He learnt this ability during his time as a Blackened Shadow during the Fourth Grail War, having absorbed the Berserker back then.

"'righty, you shitheads are scaring my Master. As her Servant, I cannot allow this, you know. Normally, I would kill you swiftly and painlessly, but today I am generous so I give you three minutes to get the hell out of this place, starting from now."

Avenger stated, having predicted the outcome. The Devils before him stared at him as if he had grown two heads before charging at him with their weapons. Avenger held Rias in his left arm and sidestepped to dodge an incoming thrust before retaliating with a stab at chest. The Devil looked at the hole on his body in horror and fell to his knees.

"Master, I advise you to find somewhere safe to hide. I will deal with these grunts." Avenger flashed a wolfish grin at Rias, who blushed at how charming it looked, and urged her to run. Rias was skeptical at first but seeing Avenger having to fend off the soldiers and look after her, she decided to follow his words. After making sure that his Master was out of sight, Avenger turned at the Devils, his body shifting violently. A sickening smirk crept on his face.

"Now then, time to die."

Rias hid behind a bookshelf. She waited for few minutes before peeking out to check what had happened. She nearly vomited at what was happening: Angra Mainyu lived up his title as God of Evil and Darkness by killing in wild ferocity and absorbing his enemies' corpses into his blackened body. The sounds of bone crushed and blood sprayed out struck fear to Rias' mind and for once, she felt sorry for her former assailants. After those short but seemingly forever minutes, Rias exited her cover and approached the calmed down Avenger, nervously poking his back to get his attention. He turned around and greeted her with the same laidback smile.

"Ah there you are, Master. How was my first performance? Is it good?"

"U-Um, Angra Mainyu-sama, I –"

"Ah I forgot to tell you. You can speak my true name freely when we are in private areas but in public, please refer me as Avenger. That's for your own safety, Master. Can't let everyone know that the God of Evil is roaming around, right?"

"Um, okay. Ehem, Avenger-sama, I have few questions for you." Rias tried to act like a heiress her family had raised her to be. Avenger did not seem to be affected much.

"Ask away, Master."

…..

"…Are you shitting me?"

"Pardon?"

"What the hell with the 'no Grail War' part?! The Summoning Ritual only works when you are chosen by the Grail! How was –" Avenger noticed something as he paused and closed his eyes. "Wait a sec, I didn't receive the information about this era when I was summoned… Does that mean, the ritual you performed was just a normal Familiar Summon one?!"

"I-I know of the ritual from this book." Rias shakily handed him the old book depicting about the ritual. He examined the front and back cover and was mortified when he saw the name of the author: Kischur Zelretch Schweinorg.

"Onore, ZELREEEEEEETCH!"

For the time being, this story will be only an one-shot. I may continue this in the future, but no promise!