It was early in COVID and American Express CEO Stephen Squeri—who had unexpectedly been named to the top job in 2016 (read the story of how, here)—was meeting with Delta CEO Ed Bastian in Atlanta to talk through the terms of their partnership.

“I fed Steve a tomahawk at the Kevin Rathbun steak house,” Bastian recalls. The conversation topic? How to “stop fighting over slices and grow the pie together,” recalls Bastian. “We came to a solution where we have one P&L, we get our percentage, and they get their percentage,” says Squeri. “And everybody’s happy.” By 2019, Squeri and Bastian achieved such comfort that they extended their partnership to the end of 2029, and the co-brand revenues have rocketed. Bastian relates that Delta collected $9 billion, more than four times the number in 2014, and though Amex doesn’t break out its revenues from the co-brand, the Delta experience suggests it’s scored a moonshot.

In fact, Squeri and Bastian clicked so well that they are now buddies in pursuing both profit and fun. They share a great deal—including their height, at well over six feet, and golf handicaps each estimates at around 12, though Squeri jests, “If he tells you he can beat me, I’ll sue!” Their big families, Catholic education, and backgrounds that were far from flush helped build the kinship. “Ed’s a guy from Poughkeepsie who went to St. Bonaventure. I’m a guy from Astoria who went to Manhattan University,” says Squeri. “He comes from a family of nine kids; I was one of four. Ed tells me about how he’d take all the clothes he could fit in a pillowcase and drive to Florida in a station wagon for spring break. I told him, ‘At least you got to go to Florida, we just got to go upstate!’” Says Bastain of Squeri, “We think a lot alike because of where we started, and part of it is having a style that isn’t hierarchical, where your people can approach you and tell you the truth.”

That comment is revealing, since Bastian is a former accountant whose extremely personable style might lead you to miss that he’s a rigorous numbers man. Squeri differs from Bastian in that he makes far fewer public appearances, but he embodies the same blend of magnetic personality and extreme rigor on the stats. Read the full story in Fortune about the ‘miracle’ Squeri has worked at Amex here, and check out Bastian’s interview on Fortune‘s podcast Titans and Disruptors here.

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