The Royal Family

What if Anna had survived and married Gabriel? And what if they were immortal? What if they modernized themselves as the centuries passed and Eve was their daughter? What would happen if Eve was mortal and her parents kept their entire life a secret? How are the Van Helsings connected to the library? And what happens when Eve is recruited to be Flynn's guardian?

Anna and Gabriel have changed their last names throughout the years to keep people from recognizing them and realizing they're immortal. It allows for them to still live in the outside world without seeming suspicious. They decided when Eve was born and since she's mortal, it was safer for her to never know of their true past. To never know of the royal family line or of creatures of myth or of magic.
As time went on, the couple befriended those from the library and worked with them until Anna gave birth. They're constantly updated on who the librarian is and who the guardian is. And after finding out about Anna's pregnancy, Gabriel rejoined the army as Gabriel Baird. He missed hunting monsters and going out on missions with his wife. But wanting to keep some past family history alive through Eve without her ever really knowing the truth, rejoining the army helped.
Eve wanted to follow in her father's footsteps joining the army when she was older. So Anna allowed for Gabriel to teach her how to fight keeping the fighting to modernized weapons and combat. And now as Eve is an adult working NATO counterterrorism as a colonial, she resigns herself to be single the rest of her life.
But what happens when she meets Flynn Carsen? The library and her parents' past along with her real heritage comes to light. How will she take being a royal princess and half arch angel? How will these heritages affect her as a colonial and guardian? And how will they affect her love for Flynn?

Story follows most of the show's timeline with the exception of Gabriel having been the one to kill Dracula in the nineteenth century