"Blue Bloods" character Joe Reagan, who died before the show's first episode, is still an important part of the series. His legacy continues through his son Joe Hill, who has followed in his father's police footsteps. However, a fan theory on Reddit suggests that Joe Reagan may not be dead after all and is instead in witness protection. While some fans are excited about the idea and its potential for new storylines, others think it doesn't make sense and undermines key moments in the series.