Mika Amonsen responds to backlash after replacing Andrew Terraciano as Sean Reagan on Boston Blue

Boston Blue is the long-running police procedural Blue Bloods, and now has one of its new faces, Mika Amonsen. Andrew Terraciano played Sean Reagan, the youngest son of the popular detective Danny Reagan, for the first 14 seasons of the show's run. Amonsen was cast in the role. Fans who grew up watching Terraciano play the part are very upset about the decision to cast someone else in the role for the new show Boston Blue. Amonsen has now talked about this fan reaction in public, explaining his thoughts on taking over such a well-known character.

The original series, Blue Bloods followed the personal and professional lives of the Reagan family, which includes several generations who are all deeply involved in New York City police work. In the spin-off show Boston Blue, Sean Reagan's life continues after he moves to Boston and tries to make his own way as a police officer, following in his family's footsteps.

Mika Amonsen on Taking up The Challenge of Taking Over the Iconic Role

In a candid interview with US Weekly on November 28, 2025, Amonsen admitted to feeling "a ton of pressure" and acknowledged the "negativity" he’s seen online:

"I definitely felt a ton of pressure at first. I felt the pressure to respect an actor before me because I wanted to respect Andrew the best I could. “There were even certain visual choices that I made that I wanted to keep in terms of hair styling and certain ways of being [as Sean]."

He further mentioned:

"I really want to maintain Sean as close as I can in the ways that I do it out of respect for this character that everyone loves — but also the character Andrew built. When I booked the show, it all happened really quickly. It was within about a week’s time and I was really thrown into it quickly. I did binge watch as much as I could and I found doing the later seasons was more helpful. I wanted to get a sense of who Sean was toward the end of the show. I really wanted to get a sense of his character at that point into adulthood and his relationship with Danny.”

To pay tribute to the character's past, Amonsen made an effort to use parts of Terraciano's performance. Even though there was a lot of pressure, the showrunners let him explore a new idea with Donnie Wahlberg, who is back as Danny. Finding comfort in things they had in common with Terraciano, like a lively energy, also helped Amonsen. He was able to keep this part of his own performance without feeling like he had to change it:

"We’re really just exploring what would have been. Of course, it is my own version of it but at the same time we haven’t seen this relationship with Sean and his dad before. He’s coming into this whole new position because from what I understand, the exploration of Sean being a cop wasn’t something that was on the table."

Sean Reagan’s Evolving Character

Sean Reagan is the younger of Danny and Linda’s two sons and the youngest of the Reagan grandchildren. Blue Bloods fans witnessed him change from a boy to a man over the course of 14 seasons. He was in a serious bike accident as a child that put him into a short coma. It was a life-threatening event that had a big impact on his family. As he got older, Sean went to a Catholic high school and played many sports, like soccer, lacrosse, and baseball, just like his older brother Jack. He usually stayed out of big trouble, but as he became a teenager, he had a time when he acted out, in part because his brother was leaving for college. During this time, he slacked off in school, got into a fight, skipped classes, and was caught drinking by the NYPD.

Sean hadn't decided on a career path before the spin-off. He once said he kind of wanted to be a fireman. But the main idea of Boston Blue depends on his choice to carry on the family tradition. After an NYPD hiring freeze stopped him from becoming a police officer in New York, he moved to Boston to try to become one. The series follows his journey. He also found his cousin Joseph Hill, who was the son of his late uncle Joseph Reagan, and invited him to the traditional family dinner.

Boston Blue episodes are available to stream on CBS.