Mika Amonsen isn’t losing sleep over the internet uproar.
The Boston Blue actor is addressing the wave of criticism that hit after he was cast as Sean Reagan in the Blue Bloods spinoff — a role previously played by Andrew Terraciano throughout the flagship CBS drama’s 14-season run before it was canceled in December 2024.
Now stepping into the shoes of Danny Reagan’s youngest son, Amonsen admits he’s seen some negativity, but he’s also noticed something else.
“There’s definitely been some pushback,” he told Us Weekly. “But when you look under those posts, you also see fans standing up for Sean and saying they’re enjoying the character I’ve created — my version of him.”
Amonsen says his priority is honoring the loyal Blue Bloods fan base. “People are loving where the show is heading with Sean, and that means a lot to me.”
Stepping Into a Legacy
Boston Blue follows Danny and Sean as they relocate to Boston, where Sean joins the police department as a patrol officer. According to the character’s IMDb page, Sean is determined to follow the Reagan family legacy — but on his own terms, in a city outside his childhood home. Danny’s choice to stay by his son’s side creates a chance for the two to rebuild their relationship in a deeper way.
Amonsen says walking into an already-beloved role came with pressure.
“I definitely felt it at the beginning,” he admitted. “I wanted to respect Andrew, so I paid attention to certain visual things — hairstyles, mannerisms — to stay true to who Sean already was.”
The Thanksgiving actor added that his goal was to keep Sean recognizable while still making the role his own. “I wanted to maintain him as closely as I could out of respect for a character everyone loves.”
Amonsen dove into research as soon as he booked the role.
“It all happened super fast — about a week,” he shared. “I binge-watched a ton of episodes, especially the later seasons, to understand who Sean had become as an adult and what his dynamic with Danny looked like.”
He also discovered similarities between himself and Terraciano.
“We’re both naturally upbeat. It was comforting to see that energy match — it meant I didn’t have to change that part of myself.”
Why the Recasting Happened
Co-showrunner Brandon Margolis previously explained the decision to recast the character.
“We love Andrew and everything he did on Blue Bloods,” he told Variety. “But this is a new chapter for both characters.”
Margolis said it wasn’t just about Sean becoming a cop — it was also Danny Reagan becoming “a father to a cop,” something the franchise had never explored. That shift, he said, opened “new storytelling lanes” and created “an organic opportunity to bring in a new performance with a new energy.”
“It’s the same character and the same relationship — but also completely different,” Margolis said. “Mika brings this vulnerability and drive to prove himself. Watching him bring Sean to life has been fantastic.”
He later told TVLine that while he “loved” seeing Terraciano grow up on television, creatively, a new energy made sense.
“It was a gamble to open the show with a new face — two new faces, actually — but the story needed viewers to connect with him immediately.”
Donnie Wahlberg’s Initial Hesitation
With Boston Blue’s first season underway, Donnie Wahlberg recently admitted he wasn’t instantly sold on returning as Danny.
“At first I was like, ‘Do I really want to do a spinoff?’” he said. “But the idea was strong, the script was strong, and I saw the opportunity to play Danny in a different way — to weave the Blue Bloods world into something new.”
Not every cast member from the original series, however, is eager to make an appearance.
