...and Molly Brown

https://www.hollywoodreporter.com/tv/tv-news/dexter-prequel-cast-revealed-1235906834/

Gibson will play a young version of Dexter Morgan in the 1991-set Paramount+ with Showtime prequel series, taking over the Michael C. Hall role. Originally titled Dexter: Origins, the prequel is now titled Dexter: Original Sin. Slater will play Dexter's father Harry, originally played by James Remar. Brown has been cast as Dexter’s sister, Debra Morgan, originally portrayed by Jennifer Carpenter.