Backstory: after cutting down the Qliphoth Vergil is sent to another world due an anomaly that happened. There he meets Azazel and forms a bond with the man as he reminds him somewhat of Dante also Azazel was able to provide him a job. (Note: no yaoi) He now teaches history at kuoh academy while keeping an eye on the supernatural especially fallen activity however this is after issei is turned into a devil.

As the sound of a bell rang through the halls of kuoh academy you could see hundreds of students leaving their class and heading out for the day. As this was happening a certain silver haired teacher could still be seeing sitting down at his class holding a book with a plain dark cover. The man was reading poems, more specifically poems made by William Blake. This man was non other than the man feared for his power and heritage, one of the twin sons of Sparda, the dark slayer, Vergil. It has been well over a week since Vergil arrived on this strange world and he found that everything in this world to be strange, especially the devils.

In his world demons and devils were not like this not to mention this world had no such beings that could be considered demons. It was devils, fallen angels and angels. Though he found it strange he has long since accepted the fact that he must live in this world until he is able to locate his original world as even the Yamato cannot take him back if he does not know the path to his world. Azazel has agreed to help him find a way to navigate through the dimensional gap to find his world should he help Azazel until then, however it may take decades to do so with everything that is happening.

Another strange thing he found a few days ago is that one of the perverts that are in the school is now part of Rias Gremorys peerage and that he is the famed red dragon emperor. Vergil would love nothing to face of against an enemy that is famed as an emperor however he knew that boy had no worth. At least in his eyes a boy who does not train nor has any power attained without hard work is worthless. And the boy was the exact thing he disliked. He has not taken training seriously and relies on his sacred gear far too much.

The same could be said about the entirety of the gremory peerage they all rely on one thing. Koneko on her strength, Kiba on his swords, Rias on her power of destruction, Akeno on her lightning. Compared to him they are nothing.

Even though he was thinking about such things he did not fail to notice the approach of one Souna shitori another of the devils residing here in kuoh academy and she was one he could tolerate and accept. He could hear the door to his classroom open.

--

Sona knocked on the second-year classroom door and entered as she heard the confirmation to enter. Siting in the teachers' chair was the homeroom teacher for one of the class as well as the academy's history teacher, and a damn good one at that.

"What brings you to my classroom, souna shitori"

The way he put emphasis on her name made her wonder if she approached him at a bad time. While deciding for new peerage members she decided that she would like to add her history teacher into her peerage. Rias questioned the reason as she could not understand what was so special about the teacher. She could not sense any power coming from the man but Sona knew something was hidden deep inside him, a power she could not understand.

"I apologise if I arrived at a bad time, sir I was merely wondering why you were still in class after school ended"

Vergil did not bother looking at her and answered

"I have work"

"I see I apologize if I disturbed you, I will take my leave now, sir"

And with that Sona left. She knew she came in at a bad time so she did not want to ask him to join peerage. She will look for a better time. Plus, there is a strange aura around him. one that puts a bit of fear into her.

Vergil knew it was almost time. He was planning on solving the fallen angel problem tonight. He stood up and left the classroom and headed straight out. He returned to his apartment and took off his work clothes and put on his battle attire, the once he prefers more his black coat and black shirt (The one he wears in dmc5) he takes out plain white mask with two blue lines going down both eye holes. It had no mouth, only eyes (think of ichigo's hollow mask after he went vasto lorde instead it has no mouth and has blue lines). He carried the mask with him just in case something unexpected happened.

Vergil set out deal with the treacherous fallens. He opened a portal with the Yamato and entered. He stood right outside the abandoned church and tried to sense any of the presences that were inside. And boy was he glad he brought the mask. Not only does the mask hide his face but it can also hide his energy which is another plus for him. He could feel the presence of three of his students and he could feel another two on their way here. He put on his mask and went to deal with the first batch of fallen he would slay tonight.

Rias and Akeno thought they would be able to defeat the fallen with no problems and regroup with the rest of the peerage. How wrong they were, just as the fight was about to end they all felt a sudden chill up their spine, the entire world suddenly felt cold as if happiness has been taken away from the world.

Dohnaseek knew what this was, this is killing intent of extreme level one that can be exerted by a monster. As the entire group turned, they saw a man clad in black holding Japanese katana on his left hand. They saw the man slowly approach the group and non-dared to speak as they were all frozen in place by the intense killing intent exerted by one man. In an instant the killing intent vanished but the man kept moving forward.

The fallen could not believe that a mere human would be able to exert such force onto them. After having their pride wounded, they decided to voice their concerns and ask the man. The devils felt the same and believed it to be a fluke and asked decided to ask, all but Mitelt raised their voice and asked "who are you"

Just as they finished, they felt a gush of wind and suddenly the mans hand was on the hilt of the blade, and in a click of the sword, Kawalraner and Dohnaseek was sliced into little pieces. Rias and Akeno simply looked in surprise and shock that a simple human was able to do this. Mitelt was frozen in fear, she had heard rumors since a week ago about a man that killed a bunch of fallen that decided to side with Kokabiel. The man simply known as the dark slayer.

Vergil looked directly at Mitlet and with a shrug he left her there and went on his way. Mitelt looked confused as she looked at him leaving. Rias on the other hand took the courage and went Infront of him and demanded he tell them his name. Vergil just looked at her and simply said "V" and he disappeared. Vergil entered the church only to find the mad exorcist has escaped but was glad his main target was still alive.

He went to the basement where he saw Rayner take the blonde nun's sacred gear. The boy, hyoudou Issei was able to achieve a new stage in his boosted gear evolution and somehow damage the fallen. However, it wasn't enough. Vergil took this moment to make his presence be known

"Fallen angel Rayner"

As the group heard his voice, they looked at him, shocked that no one was able to sense his presence

"I have questions for you, scum" Vergil said in a cold tone.

"hmph" Rayner scoffed "what do you want human"

It was at this time that Rias and her group entered the basement.

"Where is traitor Kokabiel?"

"As if I would tell you scum"

Just as Rayner said this a blue sword made of energy shot towards Rayner and stabbed her wing making her get on the ground, another sword was sent and it hit her knee causing Rayner to scream in pain.

"I will ask one more time"

As Vergil said this a Rayner was surrounded by flying blue swords spiralling around her and an intense pressure was placed on her. A cold feeling crept into everyone. The killing intent put fear into all of them.

" Where is Kokabiel"

The feeling of death was felt by Rayner. She felt an indescribable feeling, a feeling that she was infront of a demon, a demon who would kill her if she did not give him the answer he liked.

"I… I don't know"

He looked straight into her eyes. She could see his eyes glow blue under the mask. The blades stopped moving. And suddenly, all the blades stabbed into her and she screamed in pain yet did not die. Vergil, in a burst of speed and appeared infront of her with his blade drawn and held it toward the fallen. She looked up at him in fear written all over her face.

"I will ask you one more time. Where is he"

He demanded. Rayner looked at him in fear.

"I swear I don't know. He didn't tell anyone. Please, spare my life I am only doing his bidding"

She begged for her life. But Vergil looked at her cold and in a single motion of his sword he killed her. As she was dying, he looked at her and said "when the boy asked you for the nun's life did you spare her."

With that done he turned to devils who were too scared to move or even say a word. They looked at the masked man with a certain curiosity. The one who broke the silence was Issei as he ran towards Asia. Vergil saw this scene. Looked at the devils and decided it was time he left. But before he could leave, he heard Rias talk.

"Hold it right there!" Vergil stopped to look back at her.

"Who are you and what are you doing here"

"I told you. The name is V and my business here is none of your concern"

"Unfortunately for you it is. I am Rias gremory one of the two rulers of this territory"

"I already know you child, but I have no interest in what it is you have to say, I have more important business to attend to and so do you"

He said as he turned towards Asia and then looked back at Rias and disappeared.

Rias was about to say something but was cut off by him disappearing. After that Rias revived Asia and took her back to issei's place.

Asia later joined Kuoh academy and started to live with Issei and his parents. Rias was confused by the new comer and she didn't know who this masked man was but she was going to find out. She even explained the situation to Sona.

AN: The Raiser incident will happen like before since I don't see Vergil trying to help Rias with something like marriage and he seems like a person who would get along with Sona more than Rias. Also Vergil wont have romantic feelings with anyone but Sona will look up to him.