Boston Blue has chosen to replace Donnie Wahlberg’s character as the son with Mika Amonsen. Blue Bloods, which debuted in 2010, chronicled the lives of the Reagan family, many of whom serve in the NYPD under the guidance of NYC police commissioner Frank Reagan (Tom Selleck).
Frank’s father, Henry Reagan (Len Cariou), played a significant role in the series, along with Frank’s children – daughter Erin Reagan (Bridget Moynahan) and sons Danny (Wahlberg) and Jamie Reagan (Will Estes).
Danny was once married to Linda Rose Reagan (Amy Carlson), and together they had two sons, Jack and Sean, before her untimely passing. Andrew Terraciano portrayed Danny’s youngest son throughout all 14 Seasons of the Blue Bloods.
Following the conclusion of Blue Bloods in 2024, CBS revealed a spinoff named Boston Blue. The focus of this new series is Wahlberg’s character, who transitions from his role as a former NYPD officer to a position within the Boston P.D.
In this new chapter, he teams up with detective Lena (Sonequa Martin-Green), the eldest daughter of a well-known law enforcement family. In July 2025, Mika Amonsen joined the cast as Sean.
According to Brandon Margolis (Co-Creator and showrunner of the Boston Blue), “We have great admiration for Andrew and the contributions he made throughout his time on Blue Bloods. Ultimately, it was about embarking on a new chapter in both of their journeys. It’s not solely Sean who is stepping into the family business and embracing this fresh start. It’s also Danny Reagan who is now a father to a cop, a role he has never taken on before.”
Margolis referred to the switch as “an organic opportunity to introduce a fresh performance infused with new energy, aimed at highlighting that transformation.”
As per Brandon Margolis, “The writers’ room was eager to delve into ‘new storytelling avenues to explore’ with the spinoff series. While it’s the same character and the same relationship, it’s also entirely different. We appreciate what Mika has contributed to Sean, showcasing both vulnerability and a strong desire to prove himself. It’s been a fantastic experience to see it come to life.”
How Did Mika Amonsen Begin His Journey ?
Before pursuing acting, Mika Amonsen was the lead guitarist for a rock band based in the Toronto area. The band released a 10-track album and had the opportunity to open for Kim Mitchell, but Amonsen chose to shift his focus to acting instead.
According to Mika Amonsen, “It’s exhilarating, and you truly feel heard. Plus, there’s the allure of escape. I was home-schooled in a small town with only five hundred residents. The thought of breaking free, creating music, socializing, and hitting the road was a dream. Despite achieving some level of success, it soon became evident to me that pursuing music full-time is one of the most challenging paths. I have a deep empathy for musicians.”
Which Role Did Mika Amonsen Assume ?
Danny’s son Sean plays a crucial role in CBS’ Boston Blue, a spinoff of Blue Bloods. Fans of the beloved series might be taken aback to see Amonsen portraying Sean, especially since Andrew Terraciano was the original actor for the role.
Co-showrunner Brandon Margolis stood by the casting choice, expressing his admiration for watching Terraciano “grow up on TV.” In an interview with TV Insider in October, he stated, “It creatively made sense to find an actor with a different energy. And to your point, yes, it was a risk to introduce the show with a new face — actually, two new faces — but the narrative demanded that we connect with him immediately. Starting with that heroic moment that ends tragically was the perfect way to draw Danny Reagan into this universe.”
What Is The Narrative of Sean In Boston Blue ?
Boston Blue centers on Sean’s journey to climb the ranks alongside his friend and colleague Jonah (Marcus Scribner). He will receive support from Danny, who opted to remain in Boston to care for his son and continue his work with Lena at the Boston PD.
According to CBS description, “Sean has moved to Boston to embark on a new chapter as a patrolman with the Boston PD. Sean is dedicated to honoring his family’s legacy but wishes to do so on his own terms, which involves joining a department outside of his hometown. Danny’s choice to stay in Boston provides this father and son duo an opportunity to reconnect on a more profound level.”