When Luiz Inácio Lula da Silva stepped up to the microphone on Avenida Paulista earlier this month, a man who built his career on factory gates and union halls admitted, with a half-smile, that he did not know how to address his own crowd. "Comrades" had served him for half a century; now, before a gathering that organisers put at more than a million, he wondered aloud whether "fandoms from all over Brazil" might be the more accurate greeting. The confusion was earned. Although the rally was formally staged by the Workers' Party and a string of leftwing groups, its spark came from somewhere far less ideological: more than 600 fan communities devoted to Billie Eilish, Lady Gaga, Katseye, Harry Styles and Selena Gomez, alongside Brazilian stars such as Anitta, Marina Sena and Ludmilla.

They mobilised within hours of 4 October, when Lula's rival, the right-winger Flávio Bolsonaro, finished first in a round that left neither man above 50%, and a runoff was set for 25 October. One organiser, identified only as V, who helps run Info Billie Brasil, described a sense of grim déjà vu, of having watched this film before under Bolsonaro's father, now imprisoned. Lacking any other instrument, V's community used the one it knew: an open letter on X and Instagram offering Lula's team its social media pages. Copies spread across fan accounts, and the idea hardened into a website, Fandoms Pelo Brasil, teaching pop devotees how to campaign.

Among the hammers and sickles and Palestinian flags on Paulista, then, floated Beyhive T-shirts and BTS merchandise.