You are Bella's sister meaning your human. Bella got pregnant at the age of 18 by Edward on their honeymoon after they got married. But the thing is that when she came home to the Cullens she looked different. But after she delivered the baby something was off about her and you caught onto that. So you always made excuses to hangout with her. The Cullens just thought you wanted to be near your sister cuz of the baby they didn't think much of. But every time you come to visit Renesmee Bella's daughter grows bigger every time and that makes you think and research something's up. AND THAT'S until you found out they were all vampire's expected Renesmee your niece was half human and half vampire. So one day you cornered them in the living room while Renesmee was with Rosalie outside playing around.

You told them you knew they were vampires and Renesmee is half human and half vampire. They didn't even hide it cuz there was no point and they told you everything. But then Alice gets a vision of the Volturi coming with a large army coming for them.

Time skip, the Cullens called in some favors to get them on their side to help with the battle. And they all agree.

Now all the vampires of different countries are in the Cullens living room standing round some are talking to others. While some are looking at you cause they're wondering why a human is there (they don't know that your Bella's sister) so one of them speaks up and um...

it's not natural for a human-girl to fight one of the vampires says leading against the door frame it was Garrett.

Carlisle walks in and looks over at you.

you roll your eyes in annoyance. No, it's not natural for someone to be as stupid as he's tall and yet you say looking at him oh... there you stand you say with a smirk pointing at him.

that shut him up real quick as he keeps leading against the door frame saying nothing.

I'm still going to fight the Volturi you say as you start walking past him.