While Sean's character will return, Andrew Terraciano, who played Sean in Blue Bloods, won't appear in the new series. Instead, horror film actor Mika Amonsen from Whistle will take on the role. So far, only three characters from Blue Bloods have been confirmed, but many original stars have expressed interest in making guest appearances.

Boston Blue is a spinoff of the CBS hit Blue Bloods, following Donnie Wahlberg's Danny Reagan.