Oprah Winfrey may be this country’s great unifier. The media mogul’s supply of wisdom and inspiration over the years has been just as abundant as her lung capacity, and her surprise speech at the Democratic National Convention Wednesday night in Chicago was no exception—trademark bellowing included with that six-second hold on “Kamala Haaaaariiiiiiiiiiissssss!”

And as Oprah expounded on the “best of America,” she was wearing an ensemble that was perhaps the best of the night, a monochrome purple Italian silk crepe pantsuit with wide-leg trousers and a blazer with a corset-like belt, a custom look created for her by Christian Siriano. Siriano, by the way, had no idea that Oprah would be wearing his design, nor that she would even be speaking at the DNC, he tells Vanity Fair.

“It’s always funny: I’ve been dressing Oprah for a really long time. I’ve made her so many things, and suits, and gowns,” he says. “And her stylist, Annabelle Harron, who I love so much, she didn’t even tell me what it was for. I had no idea…. But when Oprah calls and asks for a suit, like, I really don’t care if she’s going to the grocery store.”

He only realized what was happening when his phone started blowing up with texts on Wednesday night, and he bolted to the DNC live stream to tune into Oprah’s speech. “I missed the opening walkout, and then I got so many people asking me if I made this suit,” he says. “I was like, ‘Oh, I did, actually!’”

“Obviously I was glued to just her talking, and I kind of forgot that I even made the look because I was listening to her speak, which was so amazing and incredible,” he says.

That mysterious call from Harron came through late last week. “It was really quick,” Siriano says. “We basically made this on Friday.”

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Harron sent Siriano a few examples of his designs that she and Oprah liked, with the directive that whatever he created should be purple, and the designer got to work.

Collaborating with Oprah, he says, has always been “really easy.”

“She’s probably one of the easiest people we ever make clothes for, which is hilarious, because she’s also one of the most famous people we make clothes for,” he says. “It’s really nice to see, and it’s my favorite part about making clothes for her. That’s why, literally, I didn’t know what it was for, and I don’t really care, because I know she will wear it, and she will feel good in it, and that’s why we do it.”

Much was made of the choice for Oprah to opt for full-on monochromatic purple, fully committing to the hue, from the thin wire rims of her eyeglasses and her eyeshadow, to her jewelry, suit, and heels. Siriano says that nobody outright mentioned the color as emblematic of political unity and the blending of the Democrats’ blue and the GOP’s signature red for a speech where Oprah told the crowd that “this election isn’t about us and them” and that “you’re looking at a registered independent who’s proud to vote again and again and again. Because I’m an American, and that’s what Americans do.” He assumed that it was a continuation of her press tour for The Color Purple, and selected a shade that felt “more regal.”

It doesn’t hurt, either, that she spoke on the same night as vice presidential candidate Tim Walz, current governor of Minnesota and noted Prince enthusiast, her outfit further serving as a nod to The Purple One.

This election’s DNC has been remarkable for the number of independent and Republican voices lending their support to the Democratic Harris-Walz ticket, and having Oprah—one of the most recognizable personalities in the world—use her distinctive and loud voice in its favor is an absolute boon. She’s an outspoken independent who was once rumored to have pitched a unity ticket to Mitt Romney (her reps later denied this), and who has supported Democrats in the past but isn’t a shoo-in for the party. She’s consistently popular and trusted, and her words aren’t taken so much as idle chatter, but as proclamations.

She was the picture of elegance onstage at the United Center, telling the audience: “I’m calling on all you independents and all you undecideds. You know this is true. You know I’m telling you the truth: that values and character matter most of all, in leadership and in life. And more than anything—you know this is true—that decency and respect are on the ballot in 2024.”

Her outfit brimmed with subtle, meaningful details—that little arced point in the center of her corset-ish belt evoked royal court dress of yore, and the thin frames of her glasses (which could easily have not been purple but were anyway) proved just how dedicated she was to that message of blurring party identities and symbology—but it succeeded as an easily decoded larger story too.

As for Siriano, who has dressed first lady Jill Biden, President Joe Biden, Michelle Obama, and Kamala Harris in the past, the work at the DNC may not yet be done. He may again find himself in the position of being surprised to see a VIP (very important politician) wearing one of his designs on the national stage. He even mentioned that he recently sent clothes to the stylish possible second lady Gwen Walz, “so hopefully something works out. You just never know.”

All in all, however, the designer says he is privileged to be part of a historic moment.

“I feel very proud to be supporting on this side.”