Contains spoilers for "Boston Blue" Season 1, Episode 1 — "Faith and Family"
Loyal "Blue Bloods" fans were upset when news broke that Danny Reagan's son Sean had been recast for the spin-off "Boston Blue," with Mika Amonsen taking the place of Andrew Terraciano. That wasn't the only change the spin-off had in store for Sean: When the first episode of "Boston Blue" dropped, viewers discovered that he was now a police officer, despite having shown no real interest in the profession on the mothership drama. Audiences are given no explanation for Sean's career choice in "Faith and Family" — we're dropped into his life after he's graduated from the academy and has established himself as a Boston beat cop. When he was last seen on "Blue Bloods" he was contemplating doing something with his arti