Canadian songwriter Simon Wilcox's catalog is full of sugar-sweet pop that gets a boost from unexpected touches, like the zipper-pull synths of Britney Spears' 2016 viral-video hit “If I'm Dancing” and the walls-closing-in vibe of blink-182's “Bottom of the Ocean.” But her credits on Carly Rae Jepsen's giddy “Cut to the Feeling” and Nick Jonas' spiteful ballad “Jealous” show she also can write sticky choruses—for songs both joyous and wounded.