Greg Brockman's story of the split with Elon Musk starts with a 'haunted mansion'

• OpenAI cofounder Greg Brockman returned for a second day of testimony at the Musk v Altman trial.
• He recalled a "celebratory" gathering where Musk's then-girlfriend, Amber Heard, served whiskey.
• Musk was excited by OpenAI's for-profit prospects — then resigned in a fight over control, he said.

In the summer of 2017, Elon Musk hosted a festive gathering for OpenAI's cofounders at his Bay Area "haunted mansion." Amber Heard, his then-girlfriend, poured the whiskey as they celebrated the company's future.

Days later, as the cofounders gathered again, Musk erupted in a bitter play for control of the company.

"He stood up, and he kind of stormed around the table," OpenAI cofounder Greg Brockman told jurors on Tuesday in the ongoing federal trial pitting Musk against OpenAI CEO Sam Altman.

In detail-rich testimony, Brockman described Jekyll and Hyde-level swings of temperament by the Tesla CEO — from happy party host one day to tantrum-throwing control freak the next.

The testimony by Brockman, a longtime Altman loyalist who is now OpenAI's president, was not only vivid but could prove strategically helpful for Altman's side.

In taking Altman to trial, Musk hopes to prove that Altman and Brockman deceived him into donating $38 million to OpenAI when it was a nonprofit dedicated to helping humanity, only to pivot to a for-profit for personal gain.

But Brockman told jurors Tuesday that throughout 2017, Musk eagerly pursued turning the company into a for-profit. Musk felt that keeping OpenAI solely nonprofit was deterring investors, including Bill Gates, Brockman testified.

"He asked Gates four times to donate, and Gates didn't even come to the office," Brockman told the jury.

Ultimately — at that second cofounder meeting, days after the party where Heard poured the group "some very good whiskey" — Musk played his big card, cash.

"It started out very pleasant," Brockman said. "I'd like you to have this Tesla painting," as a gesture of goodwill, Brockman recalled cofounder Ilya Sutskever telling Musk.

"Then the conversation turned to equity," Brockman said. "And something really changed. Something just shifted in him," Brockman said of Musk.

"And he was angry. He was upset."

Musk wanted to control OpenAI and to be its CEO, Brockman told the jury — something the rest of the founders objected to.

"At the end of the meeting, he just sat quiet for several minutes, just thinking," Brockman told jurors. "And he said, 'I decline.' He was not going to accept these terms."

Musk got up, "kind of stormed around the table," and lunged toward him, Brockman testified. "I thought he was going to hit me," Brockman told the jury.

Instead, Musk grabbed the painting of a Tesla that was behind Brockman, he testified.

Musk's final words, painting in hand, as he "started to storm out of the room," were these, Brockman said: "I will withhold funding until you decide what you're going to do."

"And then he left the August 29 meeting."

Then board member Shivon Zilis called later that night, Brockman testified, saying she had spoken with Musk and "Hey, it's not over."

But "it is wrong to give unilateral control," Brockman said of opposing Musk's terms.