Elon Musk’s past with Amber Heard is now an open book-literally. The Tesla CEO and SpaceX founder reflected on his yearlong on-and-off romance with the Aquaman actress in his eponymous new biography from Walter Isaacson. As for how Elon summed up their romance, he said, “It was brutal.” Though tech entrepreneur first met Amber after seeing her in 2013’s Machete Kills, the book said that their romance didn’t take off until four years later, after the she filed for divorce from Johnny Depp. Walter wrote that their early dates, mostly revolved around work-with Amber flying to the Tesla factory in California to surprise him on his birthday and Elon visiting her on the Australian set of Aquaman-though the two did share a passion for the nerdier side of life. “I guess I could be called a geek for someone who can also be called a hot chick,” Amber joked to the Pulitzer Prize-winning author in the biography, per People and Vanity Fair, while Walter noted in the book that the 37-year-old once spent “two months designing and commissioning a head-to-toe costume so she could role-play” for Elon, 52, after he told her that she reminded him of his favorite video game character, Mercy from Overwatch.