When Joyce suffers from unexplained headaches, Buffy suspects Dawn may be harming her, but they discover that they were caused by a brain tumor. Buffy soon discovers that the Keys protectors had turned the Key into a human biologically related to the Summers — her new sister Dawn. At the same time, they implanted in her family and friends lifelong memories of her. As a result, Buffy, and especially Joyce, begin to accept Dawn as a true part of the family. Upon learning of Joyces tumor, Buffy leaves her dorm to take care of her mother. Spike, still implanted with the Initiative chip, realizes he is in love with Buffy and begins fighting alongside the Scoobies after learning of Joyces tumor and supports Dawn when she learns of her true origins. Riley leaves Buffy in the middle of the season after concluding that she does not love him, joining a military demonhunting operation.
