Werewolf girl

12-year-old Aiden Andrews is forced to return to his former home after being expelled from his boarding school. He left when he was 7 years old, after he watched his 10-year-old sister Ariel be killed by a wolf.
But what Aiden doesn't know was that his sister was not killed, but bitten by a werewolf...
On his first night back, Aiden sees a wolf in the corridor and mistakes it for the one that 'killed' his sister. Angry and shocked, he follows it, only to see it turn into Ariel, only she is 14.
Aiden is overjoyed to see Ariel again, but then he remembers that she was a werewolf.
Ariel explains that when she was bitten, something went wrong and she was somehow cursed to slowly become a full werewolf. It takes four years, and Ariel only had 5 days left, so she could turn into a wolf at any point. But in 5 days, she would be a wolf forever.
She tells Aiden to stay away from her, but he's determined that he's not going to lose again.
He teams up with a few of his old friends and gets them to believe in werewolves again. They start trying to figure out how to end the curse, until witches and vampires come into the scene.
Aiden friends back out, and soon it's up to only Ariel and Aiden to stop the curse.
But there's an evil gang of vampires, witches and other werewolves that are determined to stop them, even if it means killing...or turning people into supernatural creatures...