Lamar, 37, and SZA, 35, have enjoyed a big brother/little sister bond ever since they became label mates on TDE Records and ascended to the top of their respective genres. Joint shows can be messy, especially when they pull a particular artist out of their comfort zone.

The rapper and R&B star are taking victory laps for smash hits and albums. But their co-headlining tour is still threaded with angst and reflection.