My Adoptive Father is my Brother?! (Liam and Niall ff. Slow updates.)

I was 3 when I last saw my brother. I haven't seen him in 13 years but what happens when I meet him but don't know that his my brother? Clarissa Anne Payne was three when Karen and Geoff sold her. Now 13 years later she goes by Clarissa Anne Johnson. She hasn't seen her real parents or even her brother - Liam Payne...