A whirlwind of empathy, optimism, and big-voiced dynamism, Rachel Platten is the kind of singer you want to have in your corner. From the tender pledge of allegiance “Stand by You” to the punchy self-empowerment anthem “Lone Ranger” to the march-time rallying cry of “Fight Song,” Wildfire is brimming with songs that bolster and embolden. Platten’s vocals are sweet and her melodies are Velcro-catchy, but the crystalline synths and jaunty piano chords belie an endearing toughness.