Keeping Up With the Kardashians returned on Thursday with the show's drama-packed season 18 premiere -- where tensions ran high between Kourtney and her sisters, Kim and Khloe, but things were surprisingly chill between Khloe and her ex, Tristan Thompson.

The same underlying grievances that have plagued the Kardashian sisters since the start of season 15 are still at play, with Kourtney feeling under appreciated and her sisters thinking she's acting selfish. This time however, the conflict escalated into a full-on slap-fight.

Meanwhile, there's less conflict and more uncomfortable uncertainty between Khloe and her ex, as they navigate their co-parenting relationship and personal boundaries. 

And that's all without mentioning how Kylie Jenner coming down with serious illness puts Kylie Cosmetics in jeopardy and leaves her mom, Kris Jenner, stuck in Paris at a runway show where Kylie is supposed to serve as the creative director but instead might be on her way to the hospital.

Here are some of the most dramatic moments and biggest takeaways from Thursday's big premiere.

Kim Kardashian Has Dinner With Tristan Thompson

There has obviously been a lot of tension between Kim and Tristan even since the whole cheating scandal and his split with Khloe. While Kim has said several times that she no longer holds any ill will toward him, they also aren't exactly close.

So, when Tristan is randomly in New York at the same time as Kim and happened to see her, she ends up asking him if he'd like to join her and her friends for dinner, and he accepts. The situation is clearly weird for her, and she even calls Khloe to make sure she's okay with it.

"I think what you're doing is nice. I think it's beyond that you invited him," Khloe tells Kim via video chat, before ultimately saying she's OK with it.

While everyone is fully expecting things to be weird, Tristan shows up by himself to eat with Kim, her friend Jonathan Cheban and a few other pals at a NYC hot spot, and the entire meal is totally chill. Kim actually walks away from the meal feeling closer to Tristan as friends than ever before.
 

Kourtney Still Feels Unappreciated and Insulted

After last season, when Kim and Khloe told Kourtney she should just quit if she didn't want to be involved, Kourtney decided to stick with the show and keep going. However, after coming back from a long vacation and jumping right back into production, it seems that Kourtney is having the same misgivings as before.

"I'm so f**king over glam. I honestly don't want to film, ever again," Kourtney offhandedly tells Khloe, who feels offended by her sister's indifference.

"She could have made the decision to quit, but she chose not to quit. Now she's here today exactly where we left off," Khloe says in a confessional about her sister's negative attitude. "It's affecting my mood that she's so miserable that we're here doing my job, which she agreed to."

Add into the mix a generally combative attitude with both her younger sisters, and a feeling that they don't respect her needs and her work ethic, it's clear that Kourtney was gearing up to explode.


Kylie Books a Big Gig and Then Can't Do It

After wanting to collaborate with Balmain and the fashion house's director, Olivier Rousteing, for years, Kylie finally gets the opportunity when he asks her to be the creative director for an upcoming Balmain runway show.

The gig would have Kylie doing the make-up for all the models with her Kylie Cosmetics line, and would even include her walking the runway herself at the end of the show. It's something she's incredibly excited about, and she even asked her sister, Kendall, to come over so she could practice doing a supermodel's makeup, and get some tips on how to walk the runway.

Kris ends up flying out to Paris, where the show is being held, to get stuff ready for Kylie -- and then gets word from home that Kylie has gotten a case of strep throat and may even need hospitalization. While Kris is worried about her daughter's health, she's even more worried about ruining Kylie's relationship with the massive fashion house.

In a panic, Kris calls Kendall to ask her to fly out to Paris immediately, but Kendall can't make it work with her schedule. Kris then calls Kim and offers her $400,000 and a flight over to Paris that night, but Kim rejects the offer, explaining that it wouldn't make sense given her KKW Beauty brand has been trying to distance itself from Kylie's Kylie Cosmetics brand. 

As the episode comes to an end, Kylie is far too ill to make it, and Kris has yet to figure out how to manage this minor catastrophe.


Khloe Asks Kim To Stop Being Friends With Tristan

While Kim may have moved on and is ready to be buddies with Tristan, Khloe isn't there yet. After they all meet up at Khloe's place for lunch, Tristan comes over to play with Baby True. However, Kim invites him to eat with them. Khloe doesn't object, but she doesn't necessarily feel comfortable with it either.

"Tristan and I have never had a dinner with True around, since all of this stuff has happened, and I think this is a really delicate time period. I'm really trying to set boundaries and not blur any lines," Khloe tells the KUWTK cameras, explaining that she doesn't want Tristan to feel like she led him on.

Later in the episode, Khloe makes herself clear to Kim, explaining, "I thought it was really nice that he came to dinner, and that you guys allowed that, but we all just don't need to be hanging out for no reason."

"It's not even been a year since out break up, so it's just a lot so soon," she adds, and Kim appreciates her stance, promising to "do better" in the future.


Kim and Kourtney Finally Throw Down

The big fight comes at the very end of the episode, when a remark from Kim -- in which she touts how hard she and Khloe work -- makes Kourtney feel slighted, and she reacts in a big way.

Kim was reflecting on Kylie's medical situation, and she remarked, "The problem is, if I was on my death bed, I would still show up."

"Mom is so used to me and Kourtney -- eh, Khloe -- going on our death beds," Kim added, explaining that is why Kris is panicking about Kylie being too sick to fly to Paris. Kim first angers Kendall by leaving her off the list, but Kourtney takes things to the next level.

"You act like I don't do s**t!" Kourtney tells Kim. "You have this narrative in your mind. ... I will literally f**k you up if you mention it again. Literally shut the f**k up"

Kim tries to laugh it off, but when Kourtney escalates things by grabbing her arms and pushing her to the ground, Kim gets really serious, really fast.

"Don't ever come at me like that, I swear to god I will punch you in the face," Kim warns, as she gets back to her feet. The pair then go at it as Khloe and Kendall try to break them apart.

The fight turns to yelling and tears as Kim and Kourtney continue to exchange blows, and the episode ends as Kim slaps her sister in the face while the pair continue to scream at one another.

Keeping Up With the Kardashians airs Thursdays at 8 p.m. ET/PT on E!

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