Just weeks after his high school graduation, on the afternoon before Father’s Day, Richard Magee Jr. returned home around 4 p.m. to find his father headed out the door. “Where are you going?” the 17-year-old asked his father, a 40-year-old Boston firefighter who typically didn’t begin his shift until 6 p.m. “There’s a big blaze, I’m headed in early to give the guys some relief,” Magee Sr. responded, in what neither father nor son realized would be their final conversation.