Ok, lemme try to write this down properly.
This is taken from my own lore in regards to Vampires in my own story Moonlight Kissed (that I am still writing. I have yet to arrive at the vamps! lolol)
My headcanon for Vampire!Arno is that the Dorians are renowned among the Assassins not only for their skills within the Brotherhood, but also for the fact that they have been Vampire Hunters for more than four generations.
Ever since the coming of the Ancient One (whose name and identity is clouded in mystery, although rumors and legends narrates of a powerful being, immortal, that carry around a golden staff whose powers are beyond imaginations), vampires and other supernatural creatures have started populating Europe first, and then spread all around the World. For these reasons, humans had found the need to defend themselves against those Creatures of Darkness, hence the birth of the Hunters Guild, a secondary branch of the Assassins’ Brotherhood that dealt specifically with the Supernatural.
The Dorian Family belonged to this Guild, just like renowned Hunters Ezio Auditore da Firenze and Bayek of Siwa had, for centuries before.
The Dorian have served the Guild faithfully, passing down their knowledge and powers from father to firstborn, generations after generations, and Arno was the last Dorian to have come into the Guild, eager to serve, side by side with his father.
One night, Charles and Arno were out together, scouting the surrounding of Versailles, where the Brotherhood has sent them to investigate about some disturbing facts: that Queen Marie Antoinette herself had been bitten and under the influence of the vampire himself.
Charles and Arno separated, to explore around and cover more ground, but this would prove to be fatal, for Charles was attacked and killed by the vampire.
Arno would hear his father’s cry of help, and find the creature still sucking on his father’s neck, stealing his life force away, drip by drip.
Blinded by rage, Arno would charge, but the vampire would have the best of him, tackling him against the wall and biting into his neck.
The Vampire would tell him that he would not kill him like he had done with his father, for it would be a destiny too swift and sweet. He wanted him to live as the same cursed creature Arno and his family had hunted down for generations.
The vampire fed him with his own blood, taken directly from the vein of his heart, and started the process of transformation.
With his dying breath, Arno looked at his aggressor, swearing that he would know no peace until he found him and killed him.
The vampire would look at him and just smirk, telling him that he was welcome to try, but that in his hundred years of non-life, no one was ever able to find him, Shay Patrick Cormac, the Ghost of the Emerald Island.
(sorry, I typed this up quickly while looking at my notes, the one I have on my phone, the rest is home! :/ I will try to write the rest later.)
