Joyce Summers, Buffy's mom found out about Buffy being a slayer in "Becoming". She took it bad, but learned to accept it. She even went on patrol with Buffy which proved to be a bad idea (She tried to burn Buffy at the stake in "Gingerbread"). Joyce had a fling with Giles in "Band Candy". Buffy found out that they slept together when she could read minds in "Earshot". Joyce developed a brain tumer in season 5 which gave her a hard time. After brain surgery in "Shadow" she was hunted by a demon form outer-space, of course Buffy killed it. Joyce was back on her feet dating a new man, when Buffy came home and found her body after she had an anurisem in "The Body".