I'm His Sister (TWD)

Rose Grimes is Rick's disowned, younger sister. She was at Carl's birth and Lori and Rick's wedding. She loved her family, but they kicked her out. Carl hadn't known her long enough to even know who she was. No one in the group other than Shane, Lori, and Rick knew she existed. Why did they disown her? How will she react when she arrives back at Hershel's farm, where she has been living, only to find her brother and his family waiting? And who is that guy with the crossbow?