Spencer's Assassin Niece (Criminal Minds Fanfic)

Spencer Reid the genius of his team, he's known for being quirky, awkward, and definitely not one for physical contact. But he wasn't the only genius in his family. In fact the brother of his father was a genius as well and that gene was also passed down to his daughter. Could explain why his father didn't 'like' Spencer growing up, having wished he had a normal son. His brother after all had become an assassin when he met his wife and had a beautiful daughter smarter than even Spencer. The two were close, Spencer admired her as a child but as they continued to grow she became sorta distant from him and soon she cut connections from him.. what happens when they find her dead body with a 16 year old girl? When he's her godfather?