Here's how Katy Perry and Taylor Swift went from friends to sworn enemies

Katy Perry just jumped into the middle of a feud between Taylor Swift and Nicki Minaj — but as it turns out, she's got her own shaky history with the "1989" singer.

Perry and Swift used to be close friends but have since become sworn enemies. Here's how.

The two were first photographed together at the 2008 VMAs, according to PopSugar. Then, PopSugar reports, their first Twitter interaction occurred:

They continued to exchange Twitter pleasantries and in 2010, the Mirror reports, Perry even joined Swift on stage in LA to perform Perry's hit "Hot and Cold." 

Then, in 2013, Swift directed one final tweet at Perry, according to Gawker. Perry never responded.

No one really noticed that the two had stopped publicly corresponding — but then, in September 2014, Swift opened up to Rolling Stone about a feud that had driven a wedge between them in 2013.

Swift was on a media blitz to support her then-new album, "1989." Rolling Stone's Josh Eells commented that "Bad Blood," a track from "1989," was angrier than the other songs.

Swift then divulged that "Bad Blood" is about another female artist. She didn't say who, but she did deliver some identifying details.

From Rolling Stone:

"For years, I was never sure if we were friends or not," she says. "She would come up to me at awards shows and say something and walk away, and I would think, 'Are we friends, or did she just give me the harshest insult of my life?'" Then last year, the other star crossed a line. "She did something so horrible," Swift says. "I was like, 'Oh, we're just straight-up enemies.' And it wasn't even about a guy! It had to do with business. She basically tried to sabotage an entire arena tour. She tried to hire a bunch of people out from under me. And I'm surprisingly non-confrontational – you would not believe how much I hate conflict. So now I have to avoid her. It's awkward, and I don't like it."

RS then got Swift to admit there was a "personal element to the conflict." Swift added, "But I don't think there would be any personal problem if she weren't competitive."

Many thought the culprit in Swift's story was Miley Cyrus. But then, Gawker reports, later in the day after the RS profile was published, Katy Perry sent out a particularly ominous tweet:

As it turns out, the incident Swift spoke of was likely a tour staffing switcheroo that one of Perry's favorite dancers talked about back in 2013.

In a profile for Australia's Examiner in 2013, Lockhart Brownlie said that he and three other dancers had left Swift mid-tour to work with Perry. This was before the feud had even gone public.

Brownlie told the Examiner that he'd worked on Swift's Red tour for the first six months. Then, he and two other dancers who'd worked with Perry before heard from her. She wanted to hire them again.

"Obviously, we were with Katy for two and a half years, she's like family to us, so we were like, 'Absolutely,'" Brownlie told the Examiner. "We weren't really dancing in Taylor's tour anyway so I had got a little bored and I really wanted to do a promo tour."

At least one of the stolen dancers was still working with Perry when she performed at the Super Bowl Halftime Show — he was the much lauded "right shark," Celebuzz reports.

Then, Swift released her video for "Bad Blood."

We already knew the song was most likely about Perry. The music video alluded further to their feud. 

In it, Swift and a brown-haired sidekick (played by Selena Gomez) fight off a bunch of bad guys together. Then, after they've beaten all of the men, the brunette counterpart turns on Swift. After that, Swift rounds up a girl group consisting of her real-life besties in hopes of exacting revenge.

Here's the video:

 And here's a post from Popsugar speculating on which aspects of it are thinly veiled knocks at Perry.

So now, we have this tweet from Perry that clearly alludes to Swift's current feud with Nicki Minaj:

Clearly, Perry noticed the physical similarities between herself and the antagonist in "Bad Blood" — and the fact that Swift's character in the video has an entire posse of famous friends, just waiting to exact their revenge. 

The video clearly has a girl-against-girl plotline. But Swift accused Minaj of "pitting women against each other" during their disagreement yesterday.

That's what Perry is finding so ironic.

But in the end, Perry's the one who's laughing all the way to the bank.

She's the world's richest female celebrity, having earned $135 million over the past 12 months. Swift clocked in at $80 million.