Desmond Harrington
“Dexter” alum Desmond Harrington will play the series regular role of Michael in Season 6 of “Elementary.” Pictured: Harrington at the premiere of “Ghost Ship” at the Mann Village Theatre in Westwood, California on Oct. 22, 2002. Kevin Winter/Getty Images

“Dexter” alum Desmond Harrington has joined the cast of “Elementary.”

According to Deadline, Harrington will play the series regular role of Michael in Season 6 of the CBS series. Michael is a recovering addict who once found inspiration to stay sober from Sherlock (Jonny Lee Miller). Michael offers to return the favor and be an ongoing support to Sherlock next season.

The timing of Michael’s introduction to the show seems perfect for Sherlock as it became apparent in the Season 5 finale that his relationship with his partner Joan (Lucy Liu) was feeling some strain.

It was revealed at the end of last season that there’s something wrong about Sherlock’s mental health. In fact, the episode concluded with Sherlock getting a brain scan after it was disclosed to the viewers that the woman he was interacting with was actually his deceased mother.

READ: Will there be a time jump in “Elementary” Season 6?

While the result of the brain scan is yet to be revealed, executive producer Rob Doherty said during an interview with Entertainment Weekly last month that Sherlock’s prognosis will impact his relationship with Joan. “Sherlock made a mistake when he decided to keep his condition from Joan,” Doherty said. “He’ll have a lot to explain and a lot to make up for.”

Even though there has been a rift between Sherlock and Joan since the former forgot to attend Shinwell’s (Nelsan Ellis) wake, Doherty said that Sherlock will eventually make amends with Joan and tell her about his mental condition.

Doherty told Entertainment Weekly that Sherlock “knows by now that problems like these are best addressed with help from friends,” so viewers will definitely see him open up about his health to his partner next season. The real question, however, is how long before Sherlock will tell Joan about it. “Has he waited too long to confide in her?” teased Doherty.

In addition to playing detective Joseph “Joey” Quinn on Showtime’s “Dexter,” Harrington’s other acting credits include USA Network’s “Shooter,” ABC’s “The Astronaut Wives Club” and The CW’s “Gossip Girl,” among many others.

The 13-episode Season 6 of “Elementary” will premiere midseason on CBS.