Long before Brandon Johnson ever thought of running for office, or even of moving to Chicago, his classmates at Ellis Middle School in Elgin called him “Mr. Mayor.” He was always the most serious young man in the room. At Ellis, he was the eighth-grade class president. In high school, he carried a briefcase. He wore a tie. He had, says his sister Andrea Johnson-Williams, “a presence.” His father, Andrew, was a pastor in the Church of God in Christ, the largest Pentecostal denomination in the United States. His congregation had 300 souls, and it was expected that one day Brandon would take over his pulpit. He was the sixth of 10 children, but his maturity and sense of purpose marked him as the heir.
When he was 19, after…