Seamus Dever, who played Detective Kevin Ryan for eight seasons of Castle, has signed on to the new Titans series being developed for a DC branded streaming service. Dever's role will be recurring, but no other details have been released.
The series is from executive producers Akiva Goldsman, Geoff Johns, Greg Berlanti and Sarah Schechter. Already cast as Dick Grayson is Brenton Thwaites, along with Anna Diop as Starfire, Ryan Potter as Beast Boy, Teagan Croft as Raven, Minka Kelly as Dove and Alan Ritchson as Hawk. The series focuses on Grayson as he moves out of the shadow of The Batman and into becoming a hero of his own. We've seen images of Thwaites in a Robin costume but expect that we'll also see him as Nightwing.
This is not Dever's only dive into the superhero genre, he will be appearing in the seventh episode of the second season of Legion on FX that is set to air this spring. It is difficult to speculate what role Dever may play on the upcoming series as the Titans have had many different heroes, supporting characters and villains over the years.
It feels like they should cast Jon Huertas as well. You can't have Ryan without Esposito.