Siblings fight but—much more importantly—they love each other. That dynamic is at the core of what makes Bebe Rexha and David Guetta such a dominant duo. Rexha and Guetta have an intuitive bond as musicians, the sort of innate ebb and flow typically reserved for lifelong friends. That level of compatibility can cause friction, but the tension is eclipsed by cohesion. The pair have repeatedly churned out smash songs together: “Say My Name” (with J. Balvin), “Hey Mama” (with Nicki Minaj) and, most recently, “I’m Good (Blue).” The chemistry between Rexha and Guetta is world-class, but their journey has been rocky at times. Rexha’s name was originally left off the marquee for “Hey Mama,” a song that—unbeknownst to the general public—w...