For my money, the two smartest people in Auditorium 17 of the AMC Empire 25 in Times Square were Karina Aguilar Guerrero and Jaylin Lugardo. They had made a pallet on the floor between the front row and the screen, with blankets, pillows and stuffed animals. They had portable phone chargers, snacks and coffee.

They were going to need every one of those supplies, and I should know — we were all there for the 31-hour “‘Avengers: Infinity War’ Marathon” being held by AMC Theaters,11 of the films in the Marvel Cinematic Universe being screenedin a row, followed by the film the event was named for.

This was for serious fans only. Ms. Guerrero and Ms. Lugardo, who were skipping two days of class, are very serious fans. They were each planning to rewatch the movies before the Friday release of “Infinity War.”But when they heard about the marathon, Ms. Guerrero decided, “That’s a lot cooler than me doing it by myself in my room.”

Plenty of other Marvel superfans came to the same conclusion. AMC devoted two screens in Times Square to the marathon (there were other locations around the country), and both sold out. That’s more than 500 tickets at $75 a pop, and some moviegoers spent more to get there; Larry Raab flew in from Salt Lake City, shelling out for an airline ticket and an Airbnb. It was his first time in New York.

“I looked to see if there were any local theaters doing it, and there weren’t,” he said. “I went to AMC’s website, and saw there were a few seats left here, and I decided to go for it. Never done anything spontaneous like that before.” (He sneaked out during the daytime movies to do some sightseeing.)

I came from only as far as Washington Heights, but felt very much a stranger in a strange land among the superfans. A casual admirer of the series (I’ve enjoyed some of the movies; others, not so much), I was interested to see what would inspire so many people to subject themselves to what sounded worrisomely close to the aversion therapy scene in “A Clockwork Orange.” But I discovered that the movies were only a part of what we were there for. (I also discovered the importance of ducking into a drugstore for a toothbrush and deodorant.)

So I stopped on the way for a Philly cheesesteak (the first of several poor culinary decisions) and arrived at the theater just before 1 p.m. on Wednesday, picking up my special-edition Avengers badge, Marvel poster andlanyard (for easy readmittance over the next day and a half).

The show began promptly at 1:30, and at times, it was like being at a rock concert where the band only played the hits. The crowd cheered, loudly and often: for the Marvel logo at the start of“Iron Man” (2008), the first film in the series; for the introductions of their favorite characters; for catchphrases, like Captain America’s “I can do this all day”; for each cameo by the Marvel Comics giant Stan Lee; for the first kiss between Steve Rogers and Betty, or Thor and Jane. (Thor’s first shirtless appearance was greeted by an audible “Day-um.”)

It wasn’t the first time fans had the opportunity to marathon their Marvel. Steven Krietzberg was at the first one, leading up to the release of “The Avengers” in 2012, as well as the 2015 “Avengers: Age of Ultron” marathon and the mini-thon before “Captain America: Civil War” a year later.Why did he choose to revisit them in a multiplex, rather than the comfort of his own home? “You get to see them the way they were meant to be seen, on the big screen,” he says. “This is pure movie magic to me.”

Others were drawn to the appeal of the shared experience. I struck up a conversation in the concession line with Oshana McCoy, who attended the pre-“Ultron” marathon and said such events offered the opportunity to plug into a community. “We’re not necessarily the most social people,” she admitted, “but you start talking to the people next to you, the people in front of you, going to the concession stand.”

Ms. McCoy attended with her sister, Jamie, and their friend Desmonae Jones, and there were several ticket holders like them — groups of friends, decked out in their best Marvel gear. There were are also pals in pairs, and couples on very long dates. And some people were flying solo. “My friends definitely aren’t interested in things like this,” Alexis Reliford said, laughing. She took two days off work for the marathon. “They think I’m weird! But coming to things like this, you kind of meet people who are like you.”

What’s more, they don’t all look like, say, someone akin to the Comic Book Guy on “The Simpsons.”

“You will see everybody here,” Ms. McCoy predicted. “The last one, we had kids in theater, senior citizens in the theater, and they stayed up the entire time.” And she was right — there wasn’t a dominant sex, race, or age in the theater. The only thing everyone had in common was that they love these movies.

As day turned into night, some slept, as I did, slumped in their upright chair, airplane-style. Takingadvantage of neighbors who had slipped out, some curled up on a series of empty seats. Others simply hit the floor, with backpacks and jackets as makeshift pillows and blankets. The overnight movies were complemented by the soft buzz of snoring, and the silence between lines was occasionally punctured by the pop of a particularly loud snort, which drew a chuckle from the bleary-eyed souls who were still awake.

When daylight broke — not that we could see it — and before “Doctor Strange” began at 10 a.m., some of us ventured out for coffee and bagels. We ate them in the lobby because the auditorium had taken on the distinct smell of day-old body odor, stale popcorn and old socks. As we ate, legends of the night were shared, of people who sneaked into empty theaters elsewhere in the multiplex and caught hours of uninterrupted sleep. The rest of us, cramped in our seats all night with our neck pillows, kicked ourselves for not thinking creatively.

By the time “Infinity War” was on deck, 28 hours in, the excitement was palpable. When the 3D seemed to be misaligned during the unwantedtrailers, I was genuinely worried there was going to be a riot. A raucous “FIX IT! FIX IT” chant filled the room before the image was quickly repaired.

When the film came to its surprisingly emotional climax, I realized how much its outcome had been augmented by the experience we’d had over the previous 30-plus hours — a community binge-watch, of the most expensive, expansive and culturally dominant series of our time, and arriving at a jaw-dropping cliffhanger.

And the Marvel Cinematic Universe is uniquely suited for our binge-watch culture: with its recurring characters, multimovie story lines, copious Easter eggs, and interlocking post-credit puzzle pieces, it demands that fans consume it all. Well, almost all. The series has now grown so expansive that six films were excluded from this year’s marathon; had every title been shown, it would have run something like 48 hours. In the homestretch, I asked my friends on the floor if that two-day commitment would have dissuaded them.

“I would’ve still been here,” Ms. Lugardo said without hesitation. “I would’ve slept through more of the movies. But yeah, I’d be here.”