Im writing a vampire story and my characters don't have a last name
So I was wondering if u could help
Okay background

Long ago, on the night of the lunar moon two vampire twins were born. The moon, shinning a bright red rose color the atmosphere made everyone delighted and in well care of the two twins. There they lived peacefully until that dark night. The twins Mercy and Soul were only two years old when a shadow cursed them and then vanished taking one of the twins with him. The night went completely black “Mercy, Soul where are you?”cried a young woman. As she ran into the room, a figure of a young man’s shadow said “Truth to be truth and evil shall remain in the heart of child with in thee.” They say that only one only one twin survived the madness of this curse.

Anyways mercy&soul don't have last names if you could help that would be awesome
Arigato minna-chii