The well-known “One Chicago” star, who takes on the role of Darren Thomas in “Castle,” is none other than “Chicago Fire” regular Taylor Kinney, who portrays Rescue Squad 3’s truck leader Kelly in the NBC drama Severides, represents. Kinney delves into the world of Castle in Season 4 Episode 17 entitled Once Upon a Crime. As it turns out, that special “Castle” episode aired in June 2012, just months before Kinney’s debut in the pilot episode of “Chicago Fire” in October of that year (via IMDb).
In the episode, Kinney’s Darren Thomas becomes involved in a case involving a string of fairytale-themed murders. One of the crimes involves a victim who was found disguised as Little Red Riding Hood with claw marks from a wild animal. Castle and Beckett initially think it might be a wolf – like in The Big Bad Wolf. When the mystery is finally revealed, Kinney’s character is freed from the grisly murders. But coincidentally, in his list of past TV credits, the actor has another direct connection to characters exhibiting wolfish behavior. As his IMDb profile reminds us, he plays the werewolf Mason Lockwood in his 10-episode series of The CW series The Vampire Diaries.