Pop stars Taylor Swift and Katy Perry were once considered "mortal enemies."

On May 7, the British media outlet Mirror delved into the relationship between Taylor Swift and Katy Perry, who are currently making headlines for their respective dating rumors and Prince Charles' coronation celebration performance.

In 2009, the two showed off their friendship by posting compliments about each other on their social networking services. Taylor Swift mentioned Katy's hit song 'Waking Up in Vegas', saying, "I love Katy Perry. I'm going to hang her poster on my wall."

Katy Perry responded, "you're as sweet as pie. Let's make a song together about what we know best."

However, trouble arose when three of Katy Perry's dancers joined Taylor Swift's tour. The dancers left Taylor Swift's tour before it ended to join Katy Perry's new tour, marking the beginning of their feud. In an interview, Taylor Swift said, "It was about business. Katy basically tried to sabotage my tour. She tried to hire people who were under me."

In 2016, Katy Perry released a video of her dancing to Kanye West's song 'Famous', which was a diss track targeting Taylor Swift.

A year later, Katy Perry apologized to Taylor Swift during a podcast, saying, "I forgive her, and I want to apologize for everything I've done."

In May 2018, before her tour, Taylor Swift posted on her social networking service, "I found this olive branch in my dressing room. It means a lot to me. Thank you, Katy," acknowledging the gift Katy Perry had given her. Since then, the two have publicly reconciled, appearing together in Taylor Swift's 'You Need To Calm Down' music video.