In January 2017, after Joe Biden swore in Kamala Harris as a U.S. senator, they posed for a traditional photo with Harris’s family. Harris, however, wasn’t done yet. She asked Biden if they could take another picture, but this time with her “extended family” — a dozen more friends and loved ones.

One of the people who came forward was Laurene Powell Jobs, one of the richest women in the world, with a fortune of over $11 billion. She stood just behind Biden’s shoulder in the picture, alongside Harris’s best friend from kindergarten and others close to her. As the photo session ended, Biden took a quick moment to chat with Powell Jobs, talking about his hopes for cancer research and even asking about her son.

It turns out that Laurene Powell Jobs is much more than just a guest in Kamala Harris’s life. Over the years, Powell Jobs has become one of Harris’s closest friends and confidantes. Not only has she offered emotional support, but she’s also contributed millions of dollars...