Sarah Michelle Gellar and Patrick Dempsey recently teased their roles in the upcoming prequel series, 'Dexter: Original Sin', through a playful Instagram selfie where they donned their character costumes. Gellar portrays Tanya Martin, the CSI chief at Miami Metro Police Department and Dexter's new boss, while Dempsey plays Captain Aaron Spencer. The series, set in Miami in 1991, explores the early years of Dexter Morgan, showcasing his transformation from student to serial killer under the guidance of his father, Harry. Gellar's caption of the photo, 'The crossover you didn’t know you needed (#McBuff?!?)', nods to their iconic roles from the '90s, Buffy the Vampire Slayer and Grey's Anatomy. The show is set to premiere on December 13 on Paramount+ with Showtime, featuring a star-studded cast including Christian Slater and Patrick Gibson. The casting choices for Gellar and Dempsey aim to evoke nostalgia for the era, heightening anticipation among fans.