The third threat to Vance is Spencer Pratt. The reality-soap performer has emerged as a disruptive force in the race for mayor of Los Angeles, churning up the city’s inert politics with performance artistry, authentic grievance and high-tech vapor. Pratt, 42, has delivered a slashing message about Democratic mismanagement of homelessness and crime, and an evocative-if-embellished personal story about losing his home in the Palisades wildfire.