Cersei is the wife of King Robert Baratheon and bore him three children that Robert and the country believe to be his, but all three are actually the children of Cersei's twin brother Jaime. Cersei's son Joffrey is now king, but, especially after Joffrey unexpectedly orders the beheading of Ned Stark, Cersei seems to be able to control him less than she believed.

Courtesy of HBO