Vinyl and Octavia are not a couple in my universe, but they lived together as neighbors for a while.
Vinyl is a vampire. She was found during the capture of the cult. During the ritual, she was made a vampire, but for some reason she has uncharacteristic features for a vampire. The Vampire Council, which controls the number of vampires. (as well as the destruction of unwanted ones), saved the child and handed him over to one of the registered vampires — a young boy working at the hospital. (I haven't decided yet whether his parents will be alive or not)
She is mute, but it is unclear whether this is her peculiarity, or the consequences of the ritual.