Two documentaries take different approaches to their star subjects. One, about the actor Val Kilmer, prefers to be hands-off. The other, about Lou Reed, welcomes complications.CANNES, France — As the documentary “Val” begins, a young, bare-chested Val Kilmer lounges on the set of “Top Gun” and claims that he’s nearly been fired from every movie he’s made. Then Kilmer’s lips twist in a smirk. He’s not playing for sympathy. He’s bragging.At the Cannes Film Festival on Wednesday, two documentaries debuted about famously prickly pop-cultural figures, but despite that promising first scene, “Val” would rather recontextualize the actor as a misunderstood softy. Perhaps you remember the stories about Kilmer, a major 1990s movie star whose career fizzled amid rumors that he was difficult to work with. Well, “Val,” directed by Ting Poo and Leo Scott, lets the 61-year-old actor retell those tales more sympathetically, in his own voice.Or, to be more precise, the voice of his son Jack, who delivers the documentary’s first-person narration. Throat cancer has ravaged Val Kilmer’s signature purr, and Jack Kilmer, an actor, is an acceptable voice substitute who nevertheless sounds far more easygoing than his father ever did. Kilmer has been recording himself since childhood, and over decades of home movies, he and his son paint the picture of an undervalued artist who always wanted to give his all, even when Hollywood wasn’t interested.Jack’s narration is so good-natured that it may take you a little while to realize that Kilmer dislikes nearly every film on his résumé that a fan might want to hear about. “Top Secret,” his first film, was “fluff” that Kilmer says he was embarrassed to appear in, and he practically had to be strong-armed into making the jingoistic Tom Cruise movie “Top Gun.” On “Batman Forever,” Kilmer claims the studio machine thwarted his attempts to deliver an actual performance, so he instead patterned his Bruce Wayne on soap-opera actors.All the while, Kilmer was recording elaborate audition tapes for the likes of Stanley Kubrick and Martin Scorsese, efforts that “Val” devotes nearly as much screen time to as the roles he actually booked. Here’s the funny thing, though: Kilmer was a much better actor in the movies he hated! In the clips of “Top Gun,” you see Kilmer at his most loose and playful because he isn’t taking anything about the movie seriously, but when we watch his “Full Metal Jacket” audition — or when he practices lines from “Hamlet,” a dream role he never got to play — Kilmer’s charisma calcifies, and he becomes far too preening and pretentious.Much of the footage in “Val,” directed by Ting Poo and Leo Scott, was shot by Kilmer over the years.Amazon StudiosSo was he as big a jerk as had been rumored? “Val” sidesteps the story about his stubbing his cigarette out on a cameraman or the “Batman Forever” director Joel Schumacher’s claim that the actor was “psychotic”; here, Kilmer simply says he quit playing Batman because the suit was too arduous. In a segment about the notorious 1996 flop “The Island of Dr. Moreau,” Kilmer portrays himself as the troubled production’s serene moral compass; you’d never know that a fed-up Brando threw Kilmer’s cellphone in the bushes and reportedly said, “Young man, don’t confuse your ego with the size of your salary.”Much is made, too, of Kilmer’s romance and marriage to the actress Joanne Whalley, though we hardly hear her speak in all of Kilmer’s home-video footage. After they divorce and he fights for more time with their children, the film lets his noble, aggrieved phone calls to Whalley play out nearly in full. I’d expect that unchallenged point-of-view from a celebrity memoir. I’m not sure I buy it in a documentary.By contrast, the new Todd Haynes documentary “The Velvet Underground,” which also debuted at Cannes on Wednesday, is all too happy to confirm every story you’ve ever heard about the singer-songwriter Lou Reed being a self-obsessed jerk. Like Kilmer, Reed claimed that anyone who beefed with him was simply interfering with his artistic process, but unlike “Val,” this film isn’t afraid to show how badly Reed wanted to be famous, and how much he resented collaborators who could wrest the spotlight from him.Todd Haynes’s documentary examines Lou Reed (center, with a reclining Andy Warhol in sunglasses), and his band, the Velvet Underground. Apple TV+Reed died in 2013, and other important figures in the film like Andy Warhol (credited with steering the early career of Reed’s band, the Velvet Underground) and the singer Nico have long since passed. Haynes isn’t interested in incorporating a lot of archival clips to bring those lost voices to life; instead, this artsy documentary lets the living members of the band, like the instrumentalist John Cale and drummer Moe Tucker, do more of the heavy lifting.“The Velvet Underground” is no conventional music documentary: For one, it uses hardly any performance footage, though some of the band’s most iconic songs, like “Candy Says” and “I’m Waiting for the Man,” play often in the background. Haynes is more invested in conjuring a vibe, placing the viewer smack in the middle of the mid-60s milieu that produced seminal figures like Reed and Warhol.And though Haynes is clearly a fan of his subject, he isn’t afraid to complicate that vibe, either. One of the film’s most welcome talking heads is the critic Amy Taubin, who recalls what was so beguiling about Warhol and Reed’s artistic scene, then adds a spiky observation: If you weren’t pretty enough, Taubin claims, all those men eventually lost interest in you.Let’s face it, famous people are narcissists: If you’re going to will yourself into fame and then stay there, it’s practically required. Haynes explores that concept in a way “Val” can’t quite bring itself to do. Even if “The Velvet Underground” is less of a comprehensive documentary and more of a perfume that lingers for a while, evoking a time and place, at least it’s not afraid to add a few sour notes in pursuit of a more full-bodied scent. More