Well over a decade ago, "The Hills" alum and future Grammy winner both worked with producer RedOne. At the time, Heidi was arguably more well known, due to her reality TV career, but Gaga had more of the songwriting chops.
Heidi recalled wanting to record a song called "Fashion," but she needed Gaga to sign off on her releasing the tune since the "Bad Romance" singer wrote it. According to Heidi, Gaga agreed. However, shortly after, a producer of 2009's "Confessions of a Shopaholic" expressed interest in using "Fashion" for the soundtrack. The MTV star claims Gaga promptly snatched the song back and released it for the film.
"'No, I'm pulling that song, and I'm recording it. It's not Heidi's anymore,'" Heidi claimed the Gaga said at the time.
While it's possible that Gaga just really liked the song, Heidi thinks something else was at play — she thought Gaga was a "hater" and suspected her of being a fan of "Hills" star Lauren Conrad, Heidi's longstanding nemesis. (Gaga actually appeared on MTV reality show once.)
Heidi also alleged that Gaga basically gave RedOne an ultimatum, declaring she would stop partnering with him if he continued working with Heidi. RedOne picked a side… Gaga's side.
"He was like, 'I'm sorry, she's my writing partner for huge things,'" Heidi claims the producer said while parting ways with her.