Transitions are never without bumps, and the debut of Boston Blue proves exactly that. The biggest point of debate is the recasting of Danny Reagan’s son, Sean Reagan. For 14 seasons on Blue Bloods, Sean was played by Andrew Terraciano, who appeared in nearly every episode. But in the spin-off, the role has been handed to newcomer Mika Amonsen.
According to the showrunners, the decision was driven by story needs. With Sean now a full fledged police officer working alongside his father in Boston, they felt the character needed “new energy” to reflect his evolution. The recast gives the writers room to refresh Sean’s arc offering opportunities to explore a more mature version of the character, reshape his bond with Danny, and introduce deeper emotional tension.
Predictably, fan reactions have been split. Some longtime viewers feel the change disrupts the emotional continuity they’ve built with Terraciano’s portrayal. Others are open to the possibilities, curious to see what Amonsen brings to the role 
new chemistry, a different acting style, and a fresh interpretation of a familiar character. Terraciano himself has reportedly expressed nothing but gratitude for his years on the show and harbors no resentment over the shift.
Recasting a beloved character is always a gamble. It risks upsetting loyal fans, but it also has the potential to reinvigorate a franchise. If Boston Blue can honor its roots while embracing its new direction, it may stand not just as a continuation, but as a compelling evolution of the Reagan legacy.