It’s a hypothetical that we come to while discussing his role in director Marielle Heller’s Can You Ever Forgive Me? The film, adapted from author (and literary forger) Lee Israel’s memoir of the same name, stars Melissa McCarthy as Israel and Grant as Jack Hock, a misanthrope and a grifter, respectively, who fall into cahoots following a serendipitous run-in at the iconic gay bar Julius’. After Grant compares Hock to a Labrador and Israel to a porcupine, I turn the animal question on him. That his answer is an animal best known for being so very bright immediately makes sense given just how effusive the Swaziland-born actor is about, well, almost everything.

For instance, at one point in our conversation—and not at my prompting—we end up talking about Grant’s backside. In a scene midway through the film, Hock (who introduces himself as “Jack Hock, big cock”) is seen getting out of bed after a fling—without a shred of clothing on. That was at Grant’s insistence.

“They scrambled around and got agents and lawyers and various things to say, ‘You have to sign a nudity clause, in case you sue us,’” the 61-year-old Game of Thrones alum recalls. “I said, ‘I’m not going to sue you—it’s my suggestion! I can’t plausibly get out of bed with somebody and be clothed.’” His only note was to cinematographer Brandon Trost: “I said, ‘Please be kind, put me in shadow. This is a 60-year-old butt-cheek that’s coming your way, and if they freeze-frame in high-definition, I want to be looked after.’” It’s a memory that Grant punctuates with a laugh, and a cheerful, “So he did!”

As per his explanation of how he found his way into playing Hock, which shifts from practical to deeply personal within seconds, Grant is almost disarmingly willing to venture into candid territory. Stepping into the shoes of a real man about whose life very little is known, Grant latched onto one of the precious few details that Israel afforded about him: that he used a short cigarette holder because he thought it would stop him from getting lung cancer. That single prop—antiquated and unusual by the 1980s, when the film is set—suggested a certain romanticism and self-confidence, and clicked with a key aspect of Hock’s lust for life.

“Once I realized that the guy was HIV-positive and that, in his final scene in the story, his death was approaching, I understood why he absolutely embraced life and lived everything for the moment, in the moment, in the day, for the day, because another day might not be coming,” Grant says. “I had friends who died of AIDS in the early ‘90s, and I remember that quality of joie de vivre underwritten by incredible desperation. That’s what I went on.”

He’s quick, however, to qualify his work. “I sound like I’m trying to aggrandize what I’ve done,” he says, sounding sheepish, “but it’s all in the script, and the reaction of playing opposite Melissa.” He doesn’t hesitate in professing his love for Heller (“such a compassionate, collaborative, all-enabling director”) and for McCarthy (“an absolute astonishingly generous, kind, emotionally present human being”). But as for his own part in it all—let’s put it this way: When he saw the finished cut of his first and arguably most famous film, 1987’s Withnail and I, he offered his entire salary to director Bruce Robinson, right then and there. “I thought I’d ruined his movie and that I would never, ever work again.”

Of course, the film speaks for itself, and, far from being the nail in Grant’s coffin, launched him into a career in Hollywood, and films like Bram Stoker’s Dracula, Gosford Park, Logan and next year's Star Wars: Episode IX.

What’s most startling about Grant, however, is how that sense of vulnerability extends past his work. The actor has previously spoken openly about his struggle with depression, crediting 18 months of psychoanalysis with saving his life when he was 42. “I was the exact same age as my father was when my mother was unfaithful to him,” Grant says, citing the incident that split his family apart and led to his father’s slide into alcoholism. “His job for the British Government had come to an end because independence had come to Swaziland, and he had a 10-year old son—and I was 42 and had a 10-year old daughter. Obviously, all this stuff just impacted in one.”

The key to getting through it (he hasn’t felt the need to return to psychoanalysis since then) was a reconciliation with his long-estranged mother. “[My psychoanalyst] said, ‘As your mother is still alive, you must do everything you can to reconcile with her,’” he explains. “It took a long time to find a bridge to do that, but when we did, it was absolutely redemptive. She said three magic words to me, ‘Please forgive me,’ which changed everything.”

It’s a strange, cosmic parallelism with the title of the film he’s now starring in, which promises to bring along another sort of change in the form of Oscar buzz—though, in what doesn’t come across as the usual awards-season guff, he finds it absolutely flabbergasting. For now, he’s content to toy with the idea of writing and directing again (his directorial debut, the semi-autobiographical Wah-Wah, came out in 2005), as well as looking after his perfume line (the product of a lifelong obsession with scent and a stymied attempt to make perfume at age 12 out of rose and gardenia petals in sugar water—to impress a girl), which he co-manages with his daughter.

Though Grant describes himself as Hock’s polar opposite, he at least has the same gift of gab (“I can talk the hind leg off a donkey”) and, despite (or perhaps because of) his faintly fatalistic streak when it comes to his work, a willingness to embrace life. His relationship with his family, his commitment to his work, the way he speaks about his characters and collaborators, the risk he took in launching a perfume line (after being told he’d lose everything, he invested all the money he’d saved by not drinking or smoking in his adult life and found himself in profit after six months: “I’ve had the last laugh! Ha ha!”)—everything, in combination with his willingness to discuss it, speaks to a tremendous sense of empathy and understanding.

And if that doesn’t all scream “flamingo” to you, know that Grant has a second answer to the animal question. A flamingo is just what he’d be if he were on land. “If I was under the water, I’d be a dolphin.”