This was an echo of another signal moment this past June, when Senator Elizabeth Warren joined Clinton for their first rally together in Cincinnati. Taking the stage, Warren shouted, “I’m here ‘cause I’m with her!” before launching into Clinton’s career-long history as a true “fighter.” This was not merely Democratic duty: Warren relished the moment.

“You know I could do this all day, right?” she said to her audience, beaming. “I could—I could!”

At the end of the speech, the two women stood on stage in their matching blue suits, fists raised in front of their Ohio audience. America had not seen campaigning like this before.

I asked Senator Amy Klobuchar about these moments. “In the past, you thought you’d have to balance it,” she told me. “That you’d need a man up there on stage, that people wouldn’t accept you without man.”

I asked Klobuchar why, and she said that having a man on stage, “would give you this air of authority. You were acceptable because you brought in a man.”

The reverse, she said, was not true—men could arrive on stage with other men in, “matching khaki pants and blue shirts” and no one would take issue with the fact that there was no woman anywhere to be seen.

But it wasn’t just pairs of powerful women on stage simultaneously, but pairs of women working together. They upended the popular and pernicious narrative about female power: the notion that women are constantly in competition with one another. Through media and entertainment, the public is often led to believe that even if women are friends, they must really, secretly, be frenemies. (Combat between women is weirdly salacious in American politics: witness the frothing earlier this year about about a possible Carly Fiorina-Hillary Clinton general election matchup).

Michelle Obama seemed to understand this view—the latent desire to see the two women as adversaries, the unspoken belief that they always have been—and began her speech by improvising a rebuttal:

I just want to take this moment publicly to thank Hillary. I mean—it takes a level of generosity of spirit to do what Hillary has done in her career in her life for our family, for this nation. And if people wonder: yes, Hillary Clinton is my friend. She has been a friend to me and Barack and Malia and Sasha. And Bill and Chelsea have been embracing and supportive from the very day my husband took the oath of office.

The same spirit—contra expectation—has been a hallmark of Warren’s time with Clinton, despite the fact that she really does remain Clinton’s most potentially devastating adversary in the party. Warren (not Tim Kaine) has ultimately proven to be Clinton’s most enthusiastic attack dog, and at a rally late last month, Clinton acknowledged as much:

I kind of expect if Donald heard what she just said, he's tweeting away. [Warren] gets under his thin skin like nobody else.

It is possibly precisely because Warren is a woman that she has been such an effective offensive linewoman for Clinton, more so than her fellow progressive in the Senate, Bernie Sanders. Warren’s shrugging off of the stereotypes about female competition—with such abandon—has made her work as a surrogate all the more powerful. (Warren, after all, never endorsed Sanders, with whom she is more naturally aligned on progressive policy.)