Once upon a time, they were good friends... They both came out into the limelight at about the same time and often complemented each other's work, and would sometimes be seen / interviewed together by the celeb. press. However their friendship started to turn sour after Taylor broke up with John Mayer, and Katy then picked him up and has been dating him on and off ever since. Then after Katy's California Dream tour in 2012 ended, some of her dancers chose to audition for Taylor's Red tour for the following year. But then Katy started organizing for her new tour for her Prism album, and she contacted those dancers to see if they'd like to come back. The catch was that the tours overlapped a little, so it would mean that they'd have to drop out of Taylor's tour early in order to join Katy's tour instead. Since the dancers had been with Katy for a longer period of time, they felt they were closer to her so they agreed to join Katy's tour and leave Taylor's one. Taylor even admitted to Rolling Stone Magazine that her latest single "Bad Blood" was written in part over that incident where Taylor felt that Katy had sabotaged her tour. Then when Katy was named to perform at the Superbowl, she had asked her tour director to help her with the performance. The problem was that he was also tour director for Taylor who had given an ultimatum that were he to help Katy, Taylor would fire him and not use his services again. Now both stars have admitted to the feud, and it seems like it is still going strong.