Fire Chief Justin Alexander thought he’d serve the rest of his career in the town he’s called home for the last half dozen years. But the fourth-generation firefighter is now serving his last week as fire chief before taking the reins as Easton’s new chief next month. “I thought I would spend the rest of my 15 years working for Plainville,” Alexander said in an interview with The Sun Chronicle. The fire chief began his career in 1998 as a call firefighter in his hometown of Raynham, where his father Donald Alexander was a fire lieutenant. He became a full-time Plainville firefighter 2004 and rose through the ranks before becoming chief in 2013 and moving to town. He saw the town weather the 2008 national financial crisis and Great Recession and gradually strengthen staffing as the town grew in population. But he said he was saddened by the rejection of tax override proposals twice in less than a year and the division it created among town residents.