Y/n, at a young age unlocked his Sacred Gear, Puppets Hand, which could create a living Puppet from someones/somethings genetic material, all with their biological ability and traits. He unlocked it the moment his mother was killed by a Stray Devil, he wanted his mother and Puppets Hand crafted a Puppet from his mother's body, but because she had just died, her soul was also binded to her puppet. His mother also had a Sacred Gear, a Simple Twice Critical, which stayed with her soul in her Puppet body, which was linked to
Y/n, meaning he could use the Twice Critical as well. This all happened when he was 7 years old.

The thing about Puppets Hand... its a lost Longinus, far more dangerous then Annihilation Maker, as any creature born from Annihilation maker could be recreated by Puppets Hand. Anyone and Anything could be recreated by Puppets Hand as long as it is Biological. No matter how powerful.

Y/n's Puppets are also Customizable, interchangeable arms for weapons, this is because Puppets Hand is a Subspecies for Y/n.

He can take a stolen Sacred gear and give it to his Puppets.

He first meets the ORC when he targets the Stray Devil Visor while Rias is doing a hero monolog before they start attacking her.

Y/n is usually seen with dulled eyes, and most of the time emotionless. But he us seen as emotionally driven, just can't seem to show them properly. There are also times where he shows extreme Anger, Rage, and Sadness. When he saw Asia Suffering during the ceremony to remove her Sacred Gear, Twilight Healing, his eyes can be seen to gain a emotional light as he called out to his Mother(who is the most loved of his Puppets) to save her, which she did, destroying the cross before the ceremony could finish. This stops this when his Mother disobeyed orders and saved His life from a incoming attack, and spoke, for the first time,"stay... away... FROM MY SON!". After that he finally began to visibly show his emotions.

When Rias' Peerage loses to Riser, Issei is in far worse Condition then in the Canon series. However Riser decides he wants to be rid of someone, a human that didn't give him the respect he deserved when he went to the human world to the ORC, Y/n. So he decides to have a duel to show how superior he is to Y/n. Y/n decides to make a deal, he wins, Rias is free to choose who she marries, if Riser Wins, he can not only kill him, but take his Sacred Gear. However, Riser is beaten, badly, and not even by Y/n's puppet, but by Y/n using his Puppet's weapons and Sacred Gears. Before he can deal the final blow, Ravel blocks him, Y/n stops right when she appears, recognizing her and stopping stunned at seeing her, giving her enough time to take her brother to safety, allowing Y/n to win the Duel.

Y/n met Ravel when he was younger, saving her from a Group of Fallen Angels. Ravel had heard about Rias going to the human world, and went there without telling anybody.

I really like this idea, please, someone use it.