Harris (Hedwg and the Angry Inch) is slated to portray a "chameleon salesman" in the final two episodes of the series, with Burtka to share a sexy storyline with Jessica Lange in the season finale.
While additional details have not been revealed, it's possible Harris and Burtka could show off their musical skills. The current season has featured musical performances from cast members Lange and Sarah Paulson.
It was also recently announced that Harris would star in his own television variety series for NBC in addition to serving as host of the 2015 Academy Awards.
It has also been reported by Entertainment Weekly that Lily Rabe will reprise her performance as Sister Mary Eunice, from "AHS: Asylum," on "AHS: Freak Show." It has not been stated how Rabe's character from the show's second season will figure in to the current plot of "Freak Show." Rabe is slated to film her scenes Halloween weekend. The fourth season of "American Horror Story," which features the return of Lange, Kathy Bates, Paulson as well as series newcomer Patti LaBelle, premiered Oct. 8 on FX.
According to FX, "'American Horror Story: Freak Show' begins its tale in the quiet, sleepy hamlet of Jupiter, Florida. The year is 1952. A troupe of curiosities has just arrived to town, coinciding with the strange emergence of a dark entity that savagely threatens the lives of townsfolk and freaks alike. This is the story of the performers and their desperate journey of survival amidst the dying world of the American carny experience."
"American Horror Story" airs Wednesdays at 10 PM on FX.