Calvin Harris and Zayn Malik are caught in a feud via Twitter over comments the former One Direction band member made about Taylor Swift. 

Things began heating up after Malik retweeted a message posted by the @FemaleTexts account that compared Harris' girlfriend to Miley Cyrus in a pejorative way. His original post included a quote by Cyrus mentioning that she has already "made [her] money" and that she doesn't care if "no one buys [her] album." Malik added that "the difference is astounding."

That's when the feud exploded:

New reports suggest that the "Bad Blood" between Malik and Swift goes back to her times dating Harry Styles. 

"When Taylor and Harry dated, Zayn never took to her," a source told Hollywood Life.

"He thought she was too goody goody for Harry and acted like she was better than everyone."

Nonetheless, Swift and Harris are rumored to be writing a song together. Although a specific track title and genre has not been announced, information has surfaced about the planning stages of their upcoming hit. 

"Taylor and Calvin have been speaking about collaborating since they started dating," an insider told The Daily Stars.

"They've had a couple of sessions jamming in the studio and are working with producer Detail."