The Real Reason Why Boston Blue Recast Sean Reagan After 14 Years

A familiar face has vanished from the Reagan dinner table. After playing Sean Reagan for 14 seasons on Blue Bloods, Andrew Terraciano has been replaced in the spinoff 'Boston Blue,' leaving fans questioning the sudden shift.

Premiering in October 2025, 'Boston Blue' follows Danny Reagan's move to Massachusetts. While the series focuses on Danny's transition, the recasting of his son, Sean, became the biggest talking point. Mika Amonsen has taken over the role, portraying Sean as a young officer in the Boston Police Department who faces a life-threatening incident in the series opener.

The Creative Drive Behind the Boston Blue Sean Reagan Recast

The decision wasn't about performance, but about a "new energy." Co-showrunner Brandon Margolis told Variety that while they loved Andrew Terraciano's work, the spinoff represents a clean break. With Sean joining the family business as a cop, the writers wanted a fresh portrayal to dramatize this significant life change and the new father-son dynamic where Danny is now the father of a fellow officer.

Terraciano revealed he learned the news on his college graduation day in May 2025. Despite the shock, he shared that Donnie Wahlberg called him personally to offer support. Terraciano remains grateful for his long tenure, stating he's happy to let someone else bring something beautiful to the role.

Newcomer Mika Amonsen Addresses the Pressure

Taking over a role with 14 years of history isn't easy. Mika Amonsen admitted to feeling immense pressure. He spent time studying the original series to understand Sean's development. While he acknowledged some initial negativity from the fanbase, he noted that many are now embracing the direction the character is taking in the new series.