In season five (2000–2001), Buffy battles the hell-goddess Glory (Clare Kramer), and fully embraces her destiny for the first time. A younger sister named Dawn (Michelle Trachtenberg) mysteriously appears in Buffy's household, her existence having been seamlessly integrated with memories of the other characters. Buffy suffers emotional turmoil throughout this season, including the realization Dawn is not actually her sister, the deterioration of her relationship with Riley, the discovery that Spike has become obsessed with her, feeling that he has fallen in love with her, and her mother's death from a brain aneurysm. While on a quest to learn more about her nature as the Slayer, Buffy is told "death is her gift, a message she has difficulty understanding until the episode "The Gift", in which she sacrifices herself to save Dawn and the world by diving into Glory's interdimensional portal and closing it.