After a comic go-around with the original vampire playboy in season opener "Buffy vs. Dracula," Buffy the Vampire Slayer's fifth season quickly established its overriding theme: the importance of family, both biological and adoptive. Kristine Sutherland -- mostly absent from season four -- returned as Joyce Summers, Buffy's mother. More importantly, series creator Joss Whedon surprised viewers with the introduction of the Slayer's teenaged sister, Dawn (Michelle Trachtenberg). Neither a long-lost sibling nor a recent adoptee, Dawn was simply dropped into the mix as if she'd always been there. As the season progressed, though, she was revealed to be The Key, an ancient force that monks had incarnated into human form, with fake memories created for everybody. The reason? So that Buffy (Sarah Michelle Gellar) would protect it from Glory (Clare Kramer), a deposed god who needed it to get back to her own hellish dimension. Rather than the usual picturesque "big bad," Glory appeared to be a well-heeled beauty, albeit one with super strength and a propensity for snacking on people's sanity. As the hellgod stalked Sunnydale in expensive pumps, her minions furiously seeking the identity of The Key, Buffy had bigger problems. Doctors discovered that Joyce was suffering from brain cancer, while Dawn accidentally learned about her true origins and freaked out. Focusing on her family and refusing to show any weakness, Buffy managed to drive boyfriend Riley (Marc Blucas) away. Of course, she had a little helping hand from Spike (James Marsters), who discovered, to his horror, that he'd fallen in love with his arch-nemesis. Although repulsed by the neutered vampire's affections, Buffy slowly grew to trust him as an ally -- especially after an unexpected death left her feeling more alone than ever. Friends Giles (Anthony Stewart Head), Willow (Alyson Hannigan), Xander (Nicholas Brendan), and Anya (Emma Caulfield) continued to serve as Buffy's inner circle, while Tara (Amber Benson) escaped from her own repressive family to become a bona fide Scooby, reinforcing the season's familial theme. When an attack from Glory left Tara drooling and helpless, Willow struck back, testing her rapidly growing magical abilities. She failed, leading indirectly to Glory's discovery of The Key's identity. With Dawn in the hellgod's clutches and the clock ticking down to the moment when Glory could use the girl's death to break down the barriers between hell and earth, Buffy reached its 100th-episode season finale. Titled "The Gift," it summed up the season's themes of family, loss, and sacrifice and left some doubt as to the show's future. Behind the scenes, financial negotiations between the show's producers and the WB network had broken down. But upstart UPN agreed to pay top dollar for two more seasons, leaving the WB with a hole in its schedule and fans overjoyed.