At one point, they were rumored to be friends.
When Briana DeJesus joined the cast of Teen Mom 2 for the show's most recent season, Kailyn Lowry seemed to be the only veteran cast member who didn't have a problem with it.
That all changed when Briana began dating Javi Marroquin, Kailyn's ex-husband and the father of her second child.
These days, Bri and Kail are bitter enemies, and it seems there's no end to their feud in sight.
Check out our rundown of the latest shots fired in this increasingly brutal war or words:
Briana & Javi: Getting Serious?
What started as a fling appears to be developing into a serious relationship. Briana and Javi have been exchanging flirty messages on Twitter, and Kailyn is understandably less than pleased.
Kailyn Lowry: Not Having It
Kail has moved on from her marriage to Javi, and she's doing her own thing these days. But it seems she's not a fan of the way Bri and Javi have been flaunting their happiness (or feigned happiness) publicly.
Is It All a Game?
Some fans suspect Bri and Javi aren't serious about their relationship and are only posting about it so frequently in order to get under Kail's skin.
Bri to Javi: Let's Get Married!
For some fans, the final straw was this tweet, in which Bri made reference to an earlier conversation that she and Javi had had about getting married.
Briana: Just Kidding About the Marriage Thing
In response to disbelief from fans, Bri later clarified that she was just joking about the marriage comments.
But the Feud Is Real
Shortly thereafter, Briana kept the feud fires burning by calling Kailyn out with some screenshots of a text conversation between Lowry and Marroquin.
It all started when Javi tweeted about going to a Golden State Warriors game with Briana. Kailyn wasn't happy about the tweet, and she let Javi know via text.
Kail to Javi: Quit Recycling Our Dates!
“I remember that trip I sent you on I’m glad you get to go again with Briana," Kailyn tweeted.
Javi: Not Big on Sarcasm
“Yeah we got matching jersey tee’s. I’m excited," Javi tweeted back, apparently missing Kailyn's sarcasm.
Briana: Calling Kail Out
All of this was documented on Twitter by Briana, who posted a screenshot of the conversation. She has since deleted that tweet.
“I hope she loves doing all the stuff me and you used to do. Take her to the shark tank at the adventure aquarium next," Kailyn tweeted. This time, Javi seemed to get the gist.
Javi Goes HAM
“Like I told you before. You hated sporting events and never wanted to do anything I love doing," Marroquin shot back.
Kailyn & Briana: Sports Haters!
"She hates sports but still is excited because I’m so excited. So new memories hold more value to me now idk why you’re being like this,” Javi continued. Dude. Maybe start picking activities your dates DON'T hate?
Tell Us What You REALLY Think, Kailyn!
“We went to Lakers game and sh-t what are you talking about… But whatever! Have funnn," Lowry texted her ex. Are we picking up on a hint of sarcasm?
Fans Loved It
Naturally, Teen Mom 2 obsessives loved that this exchange was made public. For whatever reason, Briana eventually deleted the screenshot.
Kailyn to Bri: I Just Feel Bad For You!
A source tells OK! magazine that Kailyn actually PITIES Briana. “She feels really bad that she’s so ignorant," says the insider.
"Nobody on the show really likes [Briana]," the source added. Ouch. Good thing they all film in different states!
Will It Ever Stop?
At this point, the Kailyn vs. Briana feud seems to have reached the point of no return. Will these two ever settlle their differences? Maybe, but one MAJOR development would need to take place ...
Javi Could Step Away
Javi Marroquin has been at the center of all this from the start. The situation has been described as a "love triangle," but that's not entirely accurate, as it doesn't seem that Kailyn is still in love with Javi; she just soesn't want to see him flaunting his relationship with one of her colleagues. Unfortunately, dude seems to be enjoying the attention and the ego boost (who could blame him?), so it seems unlikely he'll back away for the sake of both Kailyn and Briana.