Lost in You {Peter Pevensie}

Vivian Kirke had been living with her grandfather, Digory Kirke, since she was thirteen due to the death of her parents in a tragic fire. Now sixteen and used to having the whole mansion to herself, she is obviously not thrilled when her grandfather alerts her of the four siblings coming to stay with them, due to World War ll.
When the children arrive, she tries to be nice and gets the same in return from everyone but the oldest boy, Peter. He seems to have a big ego and doesn't take Vivian very seriously. She tries to help Peter with his studies, Peter thinks she's not smart enough to help.
Eventually fed up with him, she decides they all need a break and when Lucy suggests hide and seek, they all agree. Lucy claims to have gone to a wintry wonderland, but none of them believe her. However, they are quickly proven wrong and are thrown into a sticky situation where Vivian is forced to work with Peter. Arguments, confusing feelings, and a blooming romance stir the pot as they try to rescue Edmund and Narnia from their enemy.