Inside the Premiere for 'The Hills: New Beginnings"

Pratt says the volatile relationship between the two former friends is "very Game of Thrones-ish."

Brody Jenner and Spencer Pratt were BFFs when "The Hills" first aired on MTV from 2006-2010, but man, a lot has changed since then.

On Monday's episode of "The Hills: New Beginnings," tensions between the two former friends reached an all time high, first at a pool party celebrating Heidi and Spencer's Pratt Daddy Crystals. Yes, this is a real thing.

The gathering was held at Pamela Anderson's house -- dubbed "Brandon's mom's house" -- and while Brody showed up to support Pratt, he wasn't in the mood to get wasted. "If [wife Kaitlynn Carter] was here I'd be much more inclined to drink," he told Spencer, "she doesn't like me turnt up all the time."

In a confessional, Pratt complained about how much he missed the old Brody. "I was excited to rekindle a friendship that we once had, but ever since he got married he has changed his whole personality," said Spencer. "This is not the Brody I grew up with."

Brody, however, said he's a "responsible adult" now ... and was among the first to leave the pool party. "I can't believe how hard Brody phoned it in," Spencer said to the other guys when he left.

As he continued to vent to Brandon Lee, Spencer then put a lot of the blame on Jenner's wife, Kaitlynn Carter. "The guy is f--king clearly controlled like a f--king puppet," Pratt continued. "I love my wife, I love my baby, but I'm not a drone. You can't control me. Kaitlynn doesn't like me. In 5 years of them being together, they have a lot of parties and I see a lot of people at them and I've never been invited to one of them."

After Jenner said Pratt could be "annoying as shit sometimes" in a confessional, Spencer told the other men, "I love this guy like a real life brother, more than my own sister, and then he flips scripts. Where the f--k is my best friend?"

The fallout continued later in the episode, as the entire cast met up at a tequila bar to watch an acoustic performance from Justin Bobby. Before Brody showed up, Kaitlynn told the other women the couple was organizing a trip to Vegas to see Jenner DJ -- but Heidi Montag pointed out that Spencer wasn't invited.

Carter tried to say he had been, but Heidi wasn't buying it. "Kaitlynn is trying to BS me right now," said Montag in a confessional. "You don't help your husband when you cover up for him. Brody texted other people to come to Vegas and he never texted us."

Heidi also told Kaitlynn that Spencer was "a little upset" Brody never came to see their son, Gunnar, after he was born. Kaitlynn relayed that to her husband when he got to the party, prompting him to confront Spencer.

Saying Brody's behavior at the pool party was "the final straw," Spencer told Jenner he would have "made it a huge priority" to meet his kids if he ever had a baby.

"You're acting like a little baby," Jenner hit back. "Real Brody is not 10 tequilas deep Brody. If you want to come turn up on Friday and Saturday [in Vegas] with me ... where were you?"

But Spencer said Brody "never invited [him] to anything," referring to both his gig in Vegas and his wedding. "I didn't invite some people I've actually hung out with in the last 5 f--king years, get in line," Brody then exclaimed.

Though the two separated at this point, it was only a matter of minutes before they confronted each other again at the party.

"You may not remember, I made all the effort to try and kick it with you," Pratt told him in the middle of the event, "I'm calling all the time."

"Maybe I was really f--king hurt by you, bro!" screamed Brody. Though Pratt called the reaction "bullshit," Jenner hit back again -- "So you're the only one with feelings? It was very emotionally f--king hurtful for me that I lost one of my best friends. I'm not saying it's your fault, I'm saying it was both of our faults. I'm sorry, I apologize for all the shit I've done, can we move forward?"

Pratt answered him with a "No," before leaving the party.

Consider this battle far from over, as a preview for next week shows Jenner saying Pratt was acting "like a little bitch."