As the saying goes, you can choose your friends, but you can’t choose your family. But what happens when a family member is also a friend, even if they are as loving and magnetic as they are infuriating and inappropriate?

“A Real Pain,” writer-director-star Jesse EisenbergThe loosely autobiographical and beautifully observed comedy-drama takes a touching look at this family dynamic as mismatched cousins ​​David (Eisenberg) and Benji (Kieran Culkin) travel to Poland to visit the childhood home of their beloved and recently deceased grandmother, Dory, a Holocaust survivor.

The cousins’ journey — which begins with a Jewish heritage tour of Warsaw and Lublin, after which they split off to Dory’s rural birthplace — covers as much emotional territory as it does physical. Although the sightseeing may, at first glance, seem like a way to bring David and Benji together for a much-needed but inevitably fraught reunion, Eisenberg deftly blends the story strands in ways that are dark, funny, moving, and combustible.

But it’s Benji’s creation that proves the film’s secret; he’s one of the most vivid and compelling characters you’ll see on screen this year. Culkin, in the best turn of his career, throws himself into the role with a remarkable blend of exuberance and pathos.

A rudderless and sporadically unstable guy who hit rock bottom after his grandmother’s death (and reacted drastically), the unfiltered Benji is also the life of the party: an F-bombing whirling dervish, be damned the rules, which can charm the pants. a TSA agent, gleefully tossing a brick of weed (in Poland, no less) or transforming a sober photo shoot into a dynamic theatrical experience.

But sometimes there is a defensive and slightly cruel streak in his behavior that can overshadow his better angels (of which there are many) and test the goodwill of those around him.

In this case, that primarily includes the earnest David, a digital advertising salesman and devoted family man suffering from controlled obsessive-compulsive disorder and a low threshold for embarrassment, the latter of which Benji tests repeatedly. Benji may think David is too tight – and maybe he is – but so does Benji, but in a different, less open way.

The cousins’ complementary natures may have bonded them in their youth, and a genuine, lasting love clearly remains. But as adult travel companions, their long-standing dynamic too often creates more stress than camaraderie. When, in one of the film’s many interesting exchanges, David succinctly tells Benji, “You light up a room and then you don’t care about anything in there,” you wonder how long he’s been waiting to say that.

The other members of the touring group are also subject to Benji’s ups and downs: Marcia, divorced and melancholic (Jennifer Grey, a pleasure); Eloge, Rwandan genocide survivor and Jewish convert (a poignant Kurt Egyiawan); Mark (Daniel Oreskes) and Diane (Liza Sadovy), married in middle age; and their bookish guide James (Will Sharpe, in a nice reversal from his enigmatic role in “The White Lotus”), a British non-Jew fascinated by Jewish history.

Kurt Egyiawan, left, Will Sharpe, Kieran Culkin and Jesse Eisenberg in the film “A Real Pain.”

(Projector photos)

The funky group can’t help but be drawn to the warm, exuberant Benji – Marcia, in particular, finds him a sympathetic ear – until he has a meltdown over Jews traveling first class in a Polish train (“Eighty years ago we would have been herded into the back of these things like cattle”) or what he sees as James’ invasive information sharing in a sacred cemetery. He leaves the others stunned and David mortified until the storm cloud passes and he becomes his cheerful, talkative self again. But we can see the growing chinks in Benji’s armor with each passing setback.

For all the striking historical locations the tourists explore (enhanced by Michal Dymek’s vibrant cinematography), nothing is more striking than the group’s visit to the Majdanek concentration camp on the outskirts of Lublin. With hushed reverence (the film’s splendid, Chopin-heavy soundtrack is silent here), James escorts them through the austere and gruesome chambers of the compound, accompanied by the ghosts of his countless victims.

The sequence crystallizes James’s initial warning that this would be a tour about pain and, although Eisenberg as a filmmaker does not linger on this harrowing site, it has an outsized effect on the action, as well as on everyone’s emotions, especially Benji’s.

The cousins’ eventual arrival at the house that Grandma Dory left behind to escape the Nazis is handled in a way that is unsentimental but also believable and deeply touching, with a gentle touch that serves the arc well. the rollercoaster relationship between David and Benji.

If you know (and now you know) that the humble house seen here is the same one that Eisenberg’s great-aunt fled in 1939, it adds a strange touch of verisimilitude to the already resonant scene.

Although Culkin walks away with the film, Eisenberg gives one of his best and most heartfelt performances (his famous urgent speaking style is largely intact) as a man who has come to appreciate life’s responsibilities but who may have lost a part of himself in the process. The restaurant scene in which David, in Benji’s brief absence, tearfully reveals to their worried tour companions a range of deep feelings about his troubled cousin is breathtaking.

In continuity with his beginnings in terms of writing and directing feature films, “When you’re done saving the world, Eisenberg presents himself here as a distinctive voice, blessed with a keen visual sense, a masterful ability to juggle tones, and an innate sense of timing and rhythm.