'Endgame' will be goodbye to several characters, and as UCLA psychology professor Yalda Uhls notes: “Absolutely that can feel like real grief."


“God, it seems like a thousand years ago,” Tony Stark (Robert Downey Jr.) says in the second trailer for Avengers: Endgame. “I fought my way out of that cave, became Iron Man....”


While it hasn’t quite been a thousand years, the final installment of the Marvel Cinematic Universe’s Infinity Saga represents an unprecedented moment in movie history, partly because some of the characters who have been a consistent presence in movie theaters since 2008 might retire, or even die.


And over time, those characters have started to feel like real friends to audiences.


“It is like seeing their lives unfold alongside yours,” Molly Olis Krost, a fan and grad student from the Bay Area,said. “You feel like it is actively existing along with your own life, which it makes feel inherently more real.”


“It feels like every summer I get to check in with a bunch of my friends, as weird as that sounds,” Ratnadip Das, a fan from India, says. “They almost stop being fictional characters and become real people.”


That kind of fictional friendship has real backing by psychological research.


“Researchers have long studied a phenomenon called parasocial relationships, whereby people create intense ‘relationships’ with people they don't know, often celebrities or characters,” says Yalda Uhls, a professor in UCLA’s psychology department and former film executive at studios such as MGM and Sony. “Experiments on parasocial relationships have shown that affection for a TV character predicts their perception of how real a character is. In other words, if I like character A more than character B, I'll feel like character A is more real.”


The two central figures of the MCU, Tony Stark and Steve Rogers (Chris Evans), are expected to either die, hang up their boots or step into significantly more minor roles following Avengers: Endgame. And fans may feel, after that long of a relationship with the two, a real sense of grief.


"Absolutely that can feel like real grief,” Uhls said. “These relationships are meaningful.”


Uhls believes that such a relationship may be even more significant for young people — pointing to the Beatles as an example from the past.


“A first ‘relationship’ is often the one we remember the most, and that's what some of these parasocial relationships signify when they begin in adolescence,” says Uhls.


Krost has seen her own nephew, born two years after the MCU started, develop a powerful relationship with its characters, which in turn has led to a special bond between the two.


“I've crocheted him Iron Man gloves; I bought him a Captain America shield from a garage sale and he took it home and cleaned it himself with a baby wipe; I carried him while we were in line at Disneyland waiting to meet Spider-Man, his favorite superhero tied with Black Panther,” she says. “I was really worried about how he was going to handle watching Infinity War because he loves these characters a lot.”


She herself had a visceral reaction at Loki’s (Tom Hiddleston) demise at the beginning of Avengers: Infinity War, as he was one of her favorite characters. “It is like saying goodbye to someone you have grown up with and they can't hear you,” she explained.


“I think losing a friend is the best way to describe it,” Das says.


He points to how nearly all of the MCU films have, at the end of the credits, stated that characters “will return.” But that crutch may not be there this time.


“You say goodbye to them and then check back in after a year or two years, but because we have never really had to deal with departures, the fact that that could happen to multiple characters at the same time, whether that be death or retirement, is something hard to contend with. We’re used to looking forward, but Endgame might be the first one which makes us look back at their whole journey. I don’t think the fact that some of them might hang their boots up or die has sunk in yet.”


Even for Miyako Singer, a casual fan who really got into the MCU in the past two years — and is more invested in Chris Evans and the cultural phenomenon of it all than the superhero lore itself — deaths will be tough to face.


“I will certainly cry if Captain America dies and I bawled when Tom Holland's Spider-Man got snapped — he’s just a baby!” she says. “I think in some ways, because the MCU has been such a huge phenomenon and so widely discussed and memed, it's easy to feel like I know these characters even if I missed some installments of their journeys, and it never felt difficult to jump into it.”


It’s easy to see how the MCU has fostered such strong connections over its 11 years, as it was groundbreaking from the start. Film critic and television writer Siddhant Adlakha still remembers how significant Iron Man was, specifically Tony Stark’s reveal of his superhero identity.


“It seems quaint in retrospect, but shattering the mainstream superhero paradigm that way was a pretty big deal,” Adlakha says. “The question of what came next upon revealing a ‘secret identity,’ the likes of which I’d grown up believing was set in stone, was on my mind for quite some time.”


It was a pretty effective hook, as the MCU snowballed quickly and changed the landscape of the film industry.


Notes Anton Volkov, founder of the trailer-focused website TrailerTrack: "It's like a big TV show everyone tunes in for every single week, except on a different scale."


Avengers: Endgame opens April 26.