Last summer, Shawn Mendes and Fifth Harmony's Camila Cabello hit the road together as openers on Austin Mahone's tour. In that year since, the pair — who are 17 and 18 years old, respectively — have released lauded debut albums and scored chart-topping singles with Mendes' "Stitches" and Fifth Harmony's "Worth It."
"I honestly remember so clearly the first day we met," Cabello reminisces. "He was just playing with a guitar, and I was like, 'Hi! Nice to meet you.' We didn't really hang around much during Austin's tour. It was Shawn's first tour ever, so he was constantly working, and if he wasn't working, he was in his bus playing guitar and being a loner."
This past summer, Cabello and Mendes reconnected backstage at one of Taylor Swift's concerts. Mendes has opened for the pop star, and Cabello attended with fellow Fifth Harmony member Ally Brooke. "That was the first time we had ever really spent more than a few minutes talking to each other," she says.
"We were just backstage hanging out," Mendes adds the next day. "I pulled out my guitar and we were just messing around, not really thinking about writing a song."
The casual meeting led to the pair writing "I Know What You Did Last Summer," a soulful, conversational pop duet that has the friends evoking the styles of their favorite artists, like Ed Sheeran and John Mayer. For Cabello, the dramatic lyrical dialogue stemmed from real-life heartbreak.
"At the time, I was talking to a guy that I liked, and a friend called me two days before we wrote the song and told me he had been hitting her up and trying to flirt with her as well," Cabello reveals.
"[Shawn and I] started talking about that in the song. It's about finding out that somebody had been cheating on you, and the song is that moment right before you confront that person where you both know what's next, but it's killing the both of you."
For both, the song title's reference to the 1997 horror movie of the same name starring Jennifer Love Hewitt and Freddie Prinze Jr. was purely coincidental. "When we were writing, I remember one of us just kind of blurted out the phrase 'I know what you did last summer,'" Cabello says. "I remember while we were recording, we knew that it was a movie title because one of our friends showed us the trailer for it." The pair looked to see if they could get any lyrical inspiration from the movie, but the song and film didn't exactly connect. "We were like, 'OK, no. This is a completely different thing!'"
Another reference within the song's lyrics was also unintentional, though it ended up giving Bill Withers a songwriting credit. "When Camila did the 'I know, I know, I know,' I don't think she had even heard ['Ain't No Sunshine'] before, which was funny," Mendes says with a laugh. "I knew the song, though."Though writing the song caused Cabello and Mendes to get into a "shitload of fights," as Mendes remembers it, they consider each other to be close friends. "I am very lucky that we wrote the song because I also got a really good friendship out of that," Cabello states.
As for her girl group Fifth Harmony, Cabello's solo jaunt doesn't mean she's leaving them behind. "We are very different, and I think that the healthiest thing in a group like that is to let ourselves explore," she says. "I don't really believe in music having any sort of rulebook. That defeats the whole purpose. I feel like the more music, the better. The second album is coming out, and I also did something to express my musical interest with another artist. Both of those are great and both can live."
Cabello notes that Fifth Harmony is currently "pretty far along" in recording their sophomore LP and follow-up to their debut, Reflection, which she hopes will be released "at the top of the year," though nothing is confirmed. Recording the new album allowed her to live out another musical dream in working with superproducer Max Martin and his camp. "I literally went into the bathroom and cried," she recalls. "I couldn't believe I was having dinner and my favorite songwriters in the world were right next to me. That was a dream for sure."
On "I Know What You Did Last Summer," which appears on the expanded version of Mendes' debut album, Handwritten, both artists were able to flex songwriting muscles they had never had the chance to use before. "This is my first time writing a song with another artist, and I think this is her first experience writing a song herself, too," Mendes says. He's proud to have it as one of four new originals that were added to the album. "It's really exciting to be growing as a songwriter and as an artist. I'm feeling myself get better."