Ariana Grande wrote the song with Justin Tranter, whose resumé includes hit tunes penned for the likes of Hailee Steinfeld ("Love Myself
"), Justin Bieber ("Sorry
") and Selena Gomez ("Good For You
The pair penned "Fake Smile" on the last night of a week-long session. "It was just one of those things when the song fell out," Tranter recalled to MTV News
. "Ari's a legitimate co-writer on the song, and at one point she said, 'Stop playing, I'm getting in the booth right now. And boom! She sits down and recorded the vocals herself, which I've never seen a singer ever do."