The scene starts at a building when sun was setting. A young boy with black hair that has red highlights and red eyes was on top of the building while watching the sunset. 

Boy: The sun... it's so pretty. 

With him were a group of seen girls who were slightly older than him. 

Blonde haired girl: It's time for us to go. 

Boy: So, you're really leave me. 

Twin tailed girl: We're sorry. 

Black haired girl: We thought since we've saved you from that horrible family, you would need a new and better one. 

White haired girl: Jin was kind enough to help you out. 

Y/N: But, what about you girls? 

Cat girl: Unfortunately, we have important things to deal with. 

Brown haired girl: And we don't want to get you involved. 

Wolf girl: Sorry. 

Boy: You're just gonna abandon me? Just like that? 

Blonde haired girl: Y/N... 

Y/N: (starts crying) I was saved from that hellish nightmare because of you girls. And now you're leaving me alone again? What if something bad happened to me and I need you? 

The girls felt bad for leaving Y/N as they walked up and gave him a group hug. 

Blonde haired girl: We will never abandon you. We will always be watching over you from the shadows. We promise we'll come back for you when the time is right. 

Y/N: Alpha... 

The girls broke the hug as Alpha was smiling at him, though sadness was seen in her eyes. 

Alpha: 

(Years later) 

Outside the school of Kuoh Academy, we now see an older Y/N is sitting underneath a tree with his earbuds in, listening to some rock music. 

He felt something nudge his leg and sees his Skag, Charn. 

Y/N: (smile) Hey Charn. 

Charn: (barks and sits on his lap) 

Y/N smiled as he scratches Charn's head. He then hears screaming and sees his brother Issei along with his two perverted friends, Matsuda and Motohama yelling and running from various girls.

(P.S. I'm playing to do a TG on Issei. If you have any ideas, feel free to speak) 

Charn growls at them as Y/N calms him down. 

Y/N: Easy boy. Trust me, I don't enjoy watching my brother and his friends be complete pervs to all the girls in school either, but trust me. They've got their punishment dealt out already.

Charn snorts in agreement.  

???: Hey, there he is! 

Y/N turns to see a group of girls who are.... really big fans of his.  

Girl 1: HE'S SO CUTE OH MY GOD!

Girl 2: HE'S SO PRECIOUS!

Girl 3: HE'S AN ADORABLE BOY! 

That made Y/N blushed at this.

Girls: KYAAAAAAAAAA!!!

Girl 5: HE'S SO CUTE WHEN HE BLUSHES!

Girl 6: I JUST WANT TO PROTECT HIM FROM THE PERVERTS!

Girl 7: NOT TO MENTION HE HAS A HANDSOME FACE AND A CUTE BUTT!

Gril 8: GET HIM!

Y/N: Oh crap! Time to go boy!

Then the group of girls are now running at Y/N who runs away from them with Charn. 

(Chibi: Y/N runs away from a group of girls while Charn sits by and starts scratching himself) 

The girls then lost Y/N. 

Girl 9: Hey, where did he go? 

Girl 10: Come on, let's find him.

Then the girls nodded and left, then we saw Y/N standing on top of the tree while holding Charn.  He jumped off the tree and land on his feet while putting Charn down.

Y/N: (sighs in relief) That was a close one. 

Charn nods in agreement and then looks up at something. He tilts his head curiously and huffs at Y/N.  

Y/N: What is it Charn? 

Charn looks back up and Y/N follows his gaze to see something that makes Y/N slightly widen his eyes with a blush on his face. And what he saw, was beauty incarnate.

She was looking out a window of a tall building next to the tree. She was a beautiful young woman with silky smooth white skin, blue-green eyes and a very buxom figure. Her most distinctive feature, however, was her long, beautiful, crimson hair. He couldn't stop staring in awe of her beauty. So much that he held his breath. And she was looking directly at Y/N. 

But as soon as she and Y/N made eye contact a blush formed on both their cheeks. They stared at each other for a few minutes but it felt like an eternity. He could feel his heartbeat so hard he could feel it on his chest.

Y/N: (thoughts, blushing) Who is she this girl? Her hair, is so beautifully red. And her looks, she's making me on fire.

What she did next positively killed him. She smiled so sweetly at him. That look could kill anyone. She soon left the window view.

Y/N: (blush) Who was that? 

Charn: (bark) 

Y/N: Whoever she is, she's the definition of beauty. 

He then hears the school bell.

Y/N: Guess we'd better head to class. (looks at Charn) Stay here and wait for us Charn.

Charn barks in acknowledgment and lays next the tree. Y/N then gets up and heads inside. 

Meanwhile, Rias was sitting on a couch and looked at the chessboard in front of her, planning her next move rather intensely. She was with a young woman with violet-colored eyes and a buxom figure around the same age as Rias; very long black hair tied into a ponytail held by an orange ribbon.

Rias Gremory was blushing madly, getting the attention of her best friend Akeno. 

Akeno: Is something wrong, Rias?

Rias: Akeno... Who was that boy?

Akeno: Who?

Rias: The boy with the black hair with a strange looking dog.

Akeno: Well... If I remember right his name is Y/N L/N, he's the adopted brother of Issei Hyoudou. He's on the same year and class as Issei, but far more intelligent than him, and the girls are starting to adore him while the boys seem to not like him very much. Everyone says he's good at cooking and playing both music and video games, he's quite the fighter as well as athlete. Other than that, not much else is known about him. Why? What makes you ask about him?

Rias: Oh nothing, I just wondered if you knew who he was. That's all. (moved a white pawn piece to a new position) Checkmate.

Akeno: Awww!

Rias: You're trap was easy to see through.

Akeno: I'm sorry. I tried to make it harder for you.

Rias: It's okay, and thank you. 

Rias looks back out at the window and sees Y/N walking off. 

Rias: There's something interesting about that boy. I can't put my finger on it.

Akeno comes up and follows her gaze. 

Akeno: He does look both cute and handsome. No denial whatsoever in that. (licks her lips

Maybe I should try eating him~. 

Rias: Akeno! 

Akeno: Forgive me, Rias. I was only joking. (thoughts) Yet... 

Rias undressed herself and headed into the club shower thinking to herself.

Rias: (thoughts) Y/N L/N... I don't know who you are...but you will make an excellent servant in my peerage. 

Prologue ended. 

I hope you guys liked that prologue I did. And yes, the Seven Shadows are the ones who saved Y/N from that hellish family. If you want to know, more will be revealed soon in the next future chapters. 

But anyway, if you have any ideas for the first chapter, let me know at the comments below. Peace out and enjoy!