Justin Trudeau’s career is the stuff of 21st-century political drama, with an arc that has taken him from glamorous liberal standard-bearer to the butt of jokes by US president-elect Donald Trump and his acolytes. Trudeau burst on to the international scene in 2015, a newly elected young leader of Canada whose father had also once been a popular prime minister. And he spent the next decade building a brand around being a feminist, an environmentalist, a refugee and indigenous rights advocate, pursuing the same message of change and hope as Barack Obama. While he drew fawning reviews in the news...