Things appear to be more than fine between burgeoning young pop princesses Swift and Perry — you might even call it a mad love affair. In a now-deleted tweet reported by People, Swift shares how much she loves Perry’s “Waking Up in Vegas” video — so much that she wants to hang a poster of the “I Kissed a Girl” singer on her wall. Perry responds by extending an invitation to write a song together “about the subject we know best” for an upcoming album.

Things continue to be friendly and mutually flattering between the two in the months following, judging from a glowing social media exchange in which Perry made plans to catch up with Swift at the MTV Video Music Awards after the latter tweeted a photo at her.

During the VMAs, Perry takes Swift’s side in a tweet after Kanye West jumps onto the stage and commandeers her “Best Female Video” acceptance speech with his now infamous lines, “Yo, Taylor, I’m really happy for you and Imma let you finish, but Beyoncé had one of the best videos of all time. One of the best videos of all time!”

Swift tweets about Perry’s epic birthday party (which she attended), adding an affectionate “Happy bday, pretty girl!!” to an already effusive post about the event.

Perry graces Swift’s stage during a stop in Los Angeles for an surprise duet performance of her hit “Hot N Cold.” In a now-deleted tweet, People reported that Swift wrote, “Surprise guest at Staples Center: @katyperry!! We sang Hot N Cold and jumped up and down a lot. Katy! LA! I will always love you!”

The lovefest continues online nearly a year later when Perry replies to Swift’s tweet about her new cat, Meredith. Swift responds that she misses Perry in a now-deleted tweet, reports People.

A seemingly innocuous interview with a dancer named Lockhart Brownlie is published by Australia’s The Examiner ; however, Swifties and KatyCats alike point to this interview as the Rosetta Stone of making sense of how the two might have fallen out.

According to Brownlie — who toured with Perry for her California Dreams world tour in 2011 and was a part of her Piece of Me documentary — he and two of Perry’s other former dancers left Swift’s Red tour to join Perry for her Prism tour. Brownlie’s justification is that he was closer to Perry and that he wasn’t dancing much on Swift’s tour.

“Obviously we were with Katy for two and a half years, she’s like family to us,” he said. “So we were, like, ‘Absolutely’. 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.”

In a Rolling Stone interview, Swift reveals that her song “Bad Blood,” off her upcoming album 1989, is about a female musical artist who she won’t name, who “tried to sabotage” her tour by hiring people on her staff. From there, onlookers draw a straight line to Brownlie’s account of leaving the Red tour for Perry’s Prism tour.

Swift debuts “Bad Blood” and its accompanying music video, featuring her “squad” of very famous, very good-looking friends. The song’s lyrics are widely interpreted as Swift’s narrative about how her relationship with Perry went awry. Additionally, many fans point out that Selena Gomez’s appearance in the music video was similar to Perry’s look at the time.

While she doesn’t attend the Grammy Awards ceremony herself in 2016, Perry throws a pre-Grammys bash with Spotify. When asked by the The New York Times whether or not Swift will attend, Perry responds by confirming that an invite was extended and “it’s just up to their schedules,” an apparent move of goodwill on her part. (It’s worth noting that Swift infamously pulled her music from Spotify, which could also explain, at least in part, her reported absence from the party.)

Perry releases a new perfume, which she names “Mad Love;” some fans see this as a backhanded reference to Swift’s diss track “Bad Blood,” the chorus of which is “Baby, now we got bad blood/you know we used to be mad love.”

After it comes to light that Swift co-wrote “This Is What You Came For,” her ex-boyfriend Calvin Harris’ hit with Rihanna, Harris takes to his Twitter to criticize Swift in a series of now-deleted tweets, as well as her relationship with new beau (and now ex) Tom Hiddleston.

Things get more explicit, however, when he references the then-alleged feud between Swift and Perry, writing, “I know you’re off tour and you need someone new to try and bury like Katy ETC but I’m not that guy, sorry. I won’t allow it.”

When queried by a fan as to whether or not she would collaborate with Swift, Perry responds by saying that she would if Swift apologizes.

While attending Kanye West’s concert, Perry snaps herself dancing to “Famous” as West raps lyrics referencing Swift, which she condemned.

The day before Perry’s album drops on June 9, she reveals in an interview with NME that aside from “Swish Swish,” she still has more to say about her feud with Swift. “No one has asked me about my side of the story, and there are three sides of every story: one, two, and the truth,” she said. “I mean, I’m not Buddha — things irritate me. I wish that I could turn the other cheek every single time, but I’m also not a pushover, you know? Especially when someone tries to assassinate my character with little girls [her fans]. That’s so messed up!”

Perry drops her Space Jam-inspired music video for “Swish Swish” a day after Swift announces the release date and reveals the art for her new album, Reputation. Coincidence? With these two, who knows.

At the MTV Video Music Awards, which is being hosted by Katy Perry, the music video for “Look What You Made Me Do” debuts. While the video contains plenty of shots at those who Taylor feels have attacked her reputation, Swift appears to impersonate Perry in one scene with a similar haircut and by wearing leopard print with a pet leopard (a veiled reference to Perry’s fans who are called “Katy Cats”); she also holds a Grammy award, which some think points to the fact that Swift has won multiple Grammys, while Perry hasn’t won any despite multiple nominations. Later, Perry makes a cheeky reference to Taylor Swift’s zombie-like persona in her new music video during a monologue as the host.

Taylor Swift releases her long-anticipated album Reputation and while the bulk of the songs center around her love life, her song “This Is Why We Can’t Have Nice Things” includes a closing lyric that could reference Perry’s vocal address of their longtime association. Additionally, Taylor released two zines to accompany the album, one of which revealed that the extras in the “Look What You Made Me Do” video during the paparazzi scene (where many Swifties felt that Taylor’s persona bore a striking similarity to Perry) were dancers from her 1989 tour, in what might be a sneaky wink at how it all began.

A contestant on American Idol apologizes before telling judge Katy Perry that his musical idol is Taylor Swift, going so far as to say: “I love Taylor Swift.” Perry responds by praising Taylor’s musical talent, which many interpret as shade. “Oh, you don’t have to be sorry, I love her as a songwriter as well.”

Perry doubles down on her various statements that she wants to end the feud with Taylor Swift by sending Swift a literal olive branch and a handwritten note ahead of Swift’s first concert for her Reputation tour, which Swift shared on her Instagram story on Tuesday, May 8. Swift captioned the video “Thank you Katy.”

More than a year after Perry’s olive branch gesture, she posts an Instagram picture of a plate of cookies with the words, “peace at last” written on the plate in frosting. In the caption to the image, Perry writes “feels good” and tags Taylor Swift’s Instagram handle. In the comments, Swift replies with a comment of her own, a bunch of pink emoji hearts. for Perry’s presence at Swift’s notorious Fourth of July festivities if they’re coming back.