Fans of Blue Bloods have finally got some clarity regarding a recent casting change.
The spinoff, Boston Blue, debuted on Friday, October 17, but viewers quickly realized that Andrew Terraciano, the original Sean Regan, wasn’t in the role anymore. Instead, Mika Ammonsen has stepped in.
Brandon Margolis, one of the co-showrunners for the new series alongside Brandon Sonnier, explained the rationale behind this change during an interview. This was shared in conjunction with the launch of “Boston Blue.”
“We appreciate everything Andrew has contributed to Blue Bloods over the years,” Margolis stated regarding Terraciano, who replaced Ammonsen back in July. “We’re entering a new chapter now.”
“Sean is not the only character involved in the family business experiencing a fresh start,” he said. “Danny Regan is also stepping into a role as a father to a police officer.”
Margolis also implied there were “new directions to go” with storytelling that naturally allowed for fresh performances and added energy, which he believes emphasizes that transformation.
“The characters and relationships remain, but the approach feels entirely different,” he mentioned. “We love the vulnerability that Micah brings to Sean, along with the drive to prove himself. Watching that unfold was fantastic.”
In a separate conversation, Margolis expressed a desire to see Terraciano continue to develop on screen, but mentioned, “creatively, finding a different energy made sense.”
“Starting the show with a new face was a risk, two new faces actually, but it needed to connect instantly to tell the story,” said the co-showrunner.
Margolis added, “Introducing Danny Reagan through a heroic yet tragic moment was the ideal way to integrate him into this world.”
Blue Bloods, which premiered on CBS in 2010, ran for 14 seasons until wrapping up in December 2024. Terraciano, now 22, was featured in nearly every episode as the son of Donnie Wahlberg’s character, Danny Reagan.
Meanwhile, Boston Blue launched in February 2025, focusing on Wahlberg’s character as he collaborates with his son in the Boston Police Department.
Wahlberg, 56, discussed the new spinoff at a recent screening and Q&A on October 14, 2025, in New York City. He explained that the spinoff idea came about when two concepts collided; one involved his character relocating to Texas, and the other revolved around a new law enforcement family in Boston.
“I think they thought, ‘Why not have him move to Boston instead of Texas and join this project?'” Wahlberg reflected.
“Honestly, I didn’t think it would come together so quickly,” he admitted. “We were just enjoying reminiscing about Blue Bloods.”
The Sixth Sense actor mentioned he was initially uncertain about returning but became interested once he learned more about the project.
“Then I thought, ‘Is there really a chance for a spinoff?'” Changes seemed positive. The script was impressive,” he shared. “I saw a real opportunity to portray Danny differently.”
Wahlberg needed more assurance about “Boston Blue” until he discovered that his on-screen son was also set to become a police officer, which changed the entire dynamic compared to the original series.
“That really altered everything,” he said. “There’s a whole new landscape now.”
He added, “It’s not merely about Danny partnering with someone new; it’s about him being a father who looks out for his son’s safety and passes down lessons he’s learned.”
Boston Blue airs Fridays at 10 p.m. on CBS.
