This might sound weird, but she's my twin sister. Her name is Skylar. Skye for short. Think about is as the movie "The Uninvited" where Anna has her sister Alex, but she's really deceased.
In the movie "The Uninvited", the character Anna comes home from the hospital and she has this amazing bond with her sister, Alex. Only in the end, it turns out her sister Alex died in the fire with her mom. Skye isn't dead. I'm saying she's there, but I can only see and talk to her.