“Avengers: Endgame” is on the fast track to becoming Hollywood’s most successful title ever in China, having already raked in RMB1 billion ($148 million) in just 45 hours – more than the Chinese earnings for “Wonder Woman” and “Once Upon a Deadpool” combined. It made as much in a single hour as the entire opening weekend in China of new U.S. animated release “Wonder Park.”

Since “Iron Man” debuted in the Middle Kingdom in 2008, the Marvel films have developed a huge, devoted fan base in China as no other foreign franchise has done. It has 5.79 million followers on its official Weibo account (China’s version of Twitter). The nearly two dozen installments released in China have amassed more than $2.23 billion (RMB15 billion), accounting for about 12% of the films’ global gross.

Industry watchers attribute the franchise’s success in part to timing. It began tapping into audiences just as multiplexes began proliferating across the country, as disposable income continued to grow, and as a cohort of young people exposed to the original Marvel comic books became eager consumers.

Sky Shi, a freelance producer, noted that the Marvel films entered China at a time when there were fewer Hollywood films. The series bombarded its way into people’s hearts with numerous releases a year, creating a constant, cumulative brand presence over more than a decade. “I don’t think there’s another franchise that started so early and has had such a stable product quality and quantity,” Shi said.

By contrast, the “Star Wars” series has never gotten traction in the Middle Kingdom, since the earlier films were never released there and did not have a chance to build up a following.

Shi said also that the Marvel franchise has largely avoided the trap of overtly pandering to Chinese audiences by adding superfluous Chinese characters or elements, except for tiny roles for Chinese actors Fan Bingbing and Wang Xueqi in a special Chinese version of “Iron Man 3.” “People love Marvel precisely because it’s so different from local content,” said Shi.

Many fans are millennials born into one-child families at the height of China’s reform-and-opening-up period. They “spent their formative years reading Marvel comic books and admiring, even adulating Marvel superheroes” who suited their increasingly individualistic mindset, said a commentary on CGTN, China’s English-language state broadcaster. “Robert Downey Jr. acquired the status of a spiritual guru,” the commentary added, and “watching Marvel films, in throngs and in costumes of their admired characters, was like a ritual, a sort of coming-of-age party.”

Film critic Yu Yaqin said that the series has been boosted by its marketing, although there have been missteps, such as last year’s “Infinity War” premiere, which angered fans by featuring local singers with no connection to the film more prominently than the actual stars. “I think this is the franchise that has done the best marketing in China, which has made each release a trendy event,” Yu said. “Once it’s a trend, people are willing to chase after it whether they personally like it or not.”

“Endgame,” in particular, has also benefited from the lack of competitive Chinese content. Local production slates have been especially weak this year due to new tax regulations and a consequent lack of investor optimism in the entertainment industry.

China has rapidly built thousands of new movie theaters, but is now struggling to fill them with attractive content. “There are more and more theaters but fewer and fewer ticket sales, which makes the programming a total mess,” said former Wanda executive Jack Gao. “If the theaters don’t play these few hits, they’re dead.”

As one source joked: “Who would think that Marvel would benefit most from Chinese film regulations?”

The franchise’s incredible fan base has led Chinese movie theaters to schedule “Avengers: Endgame” screenings every 15 minutes around the clock, with 99% of all tickets sold in the entire country through Sunday projected to be for the Avengers.

“Endgame” has been highly rated across all Chinese user review platforms, including Maoyan, where more than 400,000 people gave it an aggregate score of 9.2 out of 10. “Watching this last film, I couldn’t help crying. It really feels like the end of an era!” one exclaimed in a common refrain, while another wrote: “A decade of Marvel — it represents my entire youth!”

Diehard devotees showed up at midnight screenings in costume. “I’m so excited my whole body is sweating!” said a Deadpool wannabe in full face-covering regalia.