What a difference just four years makes. The last time I sat down with Barry Keoghan, he was 22, and still best known for his role as cat-killing Wayne on Love/Hate. But even then, it was clear that the Dublin actor was destined for great things. His incredible performances exude emotional intelligence, raw vulnerability, and a uniquely wired energy that makes him enormously compelling to watch onscreen. And guess what? Hollywood agrees.

Keoghan has starred opposite Rachel Griffith in Mammal, held his own alongside Brendan Gleeson and Michael Fassbender in Trespass Against Us, stole some of the focus from Colin Farrell and Nicole Kidman in The Killing Of A Sacred Deer, and appeared in the epic historical drama Dunkirk, directed by Christopher Nolan. His filmography is rapidly growing, his choices seemingly impeccable – and so it only makes sense that he’s starring in not one, but two celebrated films this month.

American Animals is Bart Layton’s genre-defying crime drama, based on the true story of four college students who stole rare books from Transylvania University in Kentucky. An exploration of memory, entitlement and Hollywood’s glorification of crime, American Animals is wickedly clever and dizzyingly entertaining – and all the more affecting because it’s true.

But when it comes to impactful true stories, Keoghan’s other release this month is also sure to have Irish cinephiles talking. Black 47 is brilliant young Irish director Lance Daly’s revenge Western, set during the Famine. Charting one man’s quest to hunt down the British officers and Irish collaborators responsible for the eviction and death of his family during the course of the Famine, Keoghan excels as an idealistic young private torn between his position and his conscience. It is a powerful tour-de-force.

Working with so many incredible American and British actors thankfully hasn’t diminished Barry Keoghan’s Dublin accent one bit, and as I enthuse about his latest releases, he cheerfully responds with a humble “Ah, cheers love.”

It’s this combination of genuine warmth and undeniable talent that landed him a leading role in American Animals. Keoghan had been a huge fan of Bart Layton’s incredible, shocking documentary The Imposter, and how it played with form and convention. Determined to work with the director, Keoghan tweeted Layton his admiration – and the rest is casting history. As with The Imposter, Layton plays with genre in American Animals, interviewing the real men who committed the robbery, while using his actors to recreate their memories of the event – memories that are not always clear, and often contradict each other.

“I had seen The Imposter and so I knew what spin Bart was going to throw on it,” Keoghan says of the unique approach. “I had a lot of trust and faith in him to do what he did. Because it’s easy to put things down on paper and say, ‘Yeah I’m going to throw this in, have a twist there’ – but with Bart, I knew I was in for a treat.”

This trust in Layton’s vision became particularly important when it came to Keoghan’s approach to his character, as the director forbid the actors from having any contact with the men they were playing until after the film was completed.

“Bart made a bold choice, keeping us away from them,” notes Keoghan. “Because every actor wants to meet the person they’re playing, don’t they? They want to observe them, imitate them, scrape every last piece of material they can from them. But Bart saw this as us being their younger selves, whereas now, they’re older, they’ve been to prison, they have a different thought process. So, he thought meeting them would influence our performances to be more mature than needed for the age and mindset we were trying to capture.”

This difference in age, maturity and experience brilliantly comes across during the film, with Keoghan and his co-stars capturing the impulsive, egotistical and somewhat naïve attitudes of their young twenty-something characters. But interviews with the real men, who spent seven years in prison for their crimes, show a sense of melancholy, and a self-awareness borne of consequence.

The men’s involvement in the film upped the stakes for Keoghan, as not only was he playing a real person, but a person he would eventually meet and have to spend time with doing media duties. Was he intimidated taking on the role?

“There’s a certain amount of respect you have to have,” says Keoghan, “because you’re telling a story that affected a lot of people. It hurt a lot of families, it hurt the parents, the librarian, so you have to have a certain amount of respect. You do hold that in the back of your head. And it was my first time playing a real life character.”

Keoghan’s character Spencer Reinhard is in many ways the heart of the film. An aspiring artist, Reinhard is quiet and sensitive, and gets swept up in the plan by his more volatile friend, Warren Lipka (played by Evan Peters). Keoghan eventually met Reinhard after the premiere of the film, and was finally able to start understanding a man he had spent months portraying.

“Meeting Spencer was cool, we hung out with them a lot,” reflects Keoghan. ”You could see in them that they deeply regretted and were sorry for what they’d done. They also knew this story needed to be told, and were proud of it, as well. They were proud that the film doesn’t show them in a glamourised light – it shows the ugly reality of what they did.”

The film also shows the somewhat ludicrous motivation which inspired the crime. These guys didn’t need the money – but they were driven to do something wild to elevate them above what they saw as a mundane existence. They wanted to be exceptional. They wanted to be special.

“It’s like modern day culture now,” observes Keoghan sagely. “Young lads, including myself – well, maybe not myself – but with a lot of young people, there’s pressure to succeed and go to college, and get a house and a big job. There’s a certain amount of expectation. Spencer is an artist, and his problem is that he doesn’t have a problem. He doesn’t have this life experience, this traumatic life experience that he thinks every artist has – you know, Van Gogh and all of these people. So the indication is that he’s just using this – he wants to create this rollercoaster and use it to fuel his art.”

The heist took place in 2004. With the subsequent rise of social media and lifestyle blogging, young people are under more pressure than ever to have a life worth documenting.

“That’s it,” nods Keoghan. “And a lot of people buy into it. A lot of people genuinely do go off on how many followers you have. I like to go on Instagram and post things and mess about, but I wouldn’t like it to mess with how I feel about how important I am, or how worthy. That competition – ‘Oh I only have X amount of followers, but that person has more’ – isn’t healthy. You see it in younger ones, you’re talking to people and the say, ‘Oh yeah, are they on Instagram – how many followers do they have?’ It’s all about these followers and all of that fucking shit, which is annoying.”

There’s something quite painful and frustrating hearing Keoghan speak about characters who come from such a place of entitlement, with such ego-driven concerns. Spencer Reinhard and his fellow conspirators all came from generally affluent backgrounds, were attending college in the United States, and were considered to be nice, upstanding young men – a perception they were aware of, and utilised. They thought they’d get away with the robbery, because in the States, “nice” white boys get away with things all the time.

This privilege and entitlement is the polar opposite of Keoghan’s own upbringing, as he has had to fight for everything he has. Appearing on The Late Late Show earlier this year, the actor revealed that his mother suffered from drug addiction and was unable to care for her children, so he and his brother had to be taken into foster care.

“The drugs hit the area and affected all of the family, and she was one of them who got caught,” says Keoghan. “So we went into foster care, and the families were good to us – there were a few of them. Thirteen. As a kid, you don’t know what’s happening. You get attached, and then boom – let’s move over here, and let’s move here. It’s a weird one. As a kid, you don’t know what’s happening and it’s only when you’re older you can get a bit of perspective on it.”

Keoghan’s mother died when she was just 30.

“I’ve great memories of her,” he says. “I’m very proud of her.”

The actor explains that while it was a hard experience, it contributed to his determination and work ethic – it was formative but doesn’t define him.

“It’s not the ideal way to grow up, but it has made me who I am,” he says. “I lived with my auntie and my grandma since I was ten, and they looked after me. So it was a part of my life, but not all of it. I was never going to let it hold me back.”

He’s actually written a script called Quick Judgement, which touches on his experiences.

“It’s about saying no matter what background people come from, you shouldn’t judge them,” says Keoghan. “Because they could have an underlying talent or skill, or just be really decent people. It’s still in the works, and I’ve loved writing it. I love even writing the backgrounds for some of my characters, so my writing comes from my acting. I want to keep doing both.”

Given the hardship he has had to overcome in his own life, I ask if Keoghan found it difficult to empathise with Reinhard and the other men involved in the robbery – after all, they were literally creating problems for themselves, while Keoghan has had to survive them. Barry’s answer is a perfect blend of his personality; the empathy and emotional intelligence of him as an actor, leavened with a dash of straight-talking Dublin realism.

“Me and Spencer related in that we were trying to prove ourselves,” he says. “With Spencer, he’s trying to prove that he can be an artist, even if he doesn’t have the troubled past or whatever. So we related in that sense, trying to overcome what people thought we could be.”

He laughs. “But yeah, we definitely ran with a different crowd and came from a different background! It was hard to fit into the ‘dudes’. Bart said at one stage, ‘When we look in your eyes, Barry, there’s a lot going on. When we look in Spencer’s eyes – there’s not much!’”

Keoghan laughs again. “So it was an interesting one to get into.”

Does Keoghan use his own personal experiences to flesh out his characters?

“Subconsciously you’re drawing on experiences,” he muses. “You’re drawing on pain or difficult moments, but not consciously. You’re not reading a script saying, ‘Oh I’m going to use this, or I’m going to pretend to be back here again’. That’s what a lot of good actors can do; tap into a moment of pain or excitement or anger and just switch it on. It’s not a technical process, it’s on a more subconscious level where you’re harnessing emotion. And I’m drawn to characters who internalise a lot.”

Growing up in Dublin’s inner city with that lack of stability in his home life, it seems like it could have been easy for Keoghan to lose his way. Still, he insists that the people around him wanted to do great things – they just didn’t always know how.

“A lot of the lads and people from the inner city, they have a lot of respect for each other and there’s a lot of confidence there,” he says. “There is a lot of belief that if you want to do something, you can do it. But the problem is the lack of opportunities. If opportunities are given, these people will take them. We’ve great footballers from the area, great filmmakers, great boxers – and these are from little opportunities that arrived and people jumped on them. That’s the same with me. There was a little opportunity given and I jumped on it. It’s not necessarily people sitting around going, ‘Oh I don’t want to do anything’ – it’s the lack of opportunity.

“And visibility,” he continues. “Some people don’t know anyone else who has gone to college, so they don’t know how that path looks or how to get on it – and then it goes the other way, too. People haven’t seen people succeed, so don’t think you can. It’s the stereotypes – I could walk in somewhere in a tracksuit looking for a job and I’ll have more work experience than the person looking at me, but you’re looked down on because of your accent and what you’re wearing.”

At 18, Keoghan studied at The Factory, the acting school whose graduates include Peter Coonan, Jack Reynor and Brian Gleeson. It was here that Barry honed his abilities. Free to express himself and develop his skills, The Factory captured his imagination and encouraged his talents in a way school never did.

“In school, I wasn’t the most intelligent person!” he laughs. “I did plays, but when I started misbehaving, they took all that away from me. I didn’t finish school, so people probably didn’t take me seriously. But then I got a part in a film called Life’s A Breeze. It was a tiny part, but I got to go to Sweden to film it. Once people saw that I was getting these opportunities and I was serious about it, they started taking me seriously too. But it’s a brave thing to say you want to be an actor here – people think you’re dreaming.”

Since Keoghan’s rapid ascent to fame, he has found nothing but support at home.

“When I’m home, it’s a lot of ‘Get me a drink, Hollywood!’ They laugh at it, in a good way,” he says. “Everyone who is close to me has remained the same. That’s the nice thing about it. They’re excited to find out what some actors are like in person, but that’s it – it’s excitement and pride, rather than begrudging. But is a weird one, that someone they know got out and is doing all this stuff – and I don’t just mean in my neighborhood. It’s not heard a lot about in Ireland, for lads to go away and do that.”

For Keoghan, who has always been a fan of boxing, there’s one man who epitomises the heights you can reach when you combine talent with ambition, and that’s Conor McGregor.

“Conor McGregor for me would be very, very inspiring,” says Keoghan, almost reverentially. “He’s just a lad from Dublin, but that man went and made history, and he’s going to keep making history. He shows that if you have the heart and the imagination and the drive and ambition – if you can picture it, you can do it. That’s where I got my ambition, even when I was a kid. I always wrote down things, always said I was going to go do this, do that. So when I saw Conor McGregor making it, it kind of inspired me to push hard and do it. That’s important.”

And where did Keoghan’s own ambition and drive spring from?

“It’s the nothing to lose attitude, isn’t it? Because I’ve been at the bottom. The bottom of the bottom, and I really mean that. And when you’ve been down so low, you can only go up. It sounds clichéd, but it came from a nothing-to-lose attitude.”

It’s certainly working for him: he continues to be a favourite with critics and fans alike. Even the small role he plays as a young private in Lance Daly’s Famine-is getting a special mention in reviews. Keoghan was delighted to appear in what is one of the first Irish films about the Famine.

“The thing about this Famine movie is that it’s going to get people talking and educate us a little bit,” he says. “Because a lot of people don’t know a lot about it – and that’s speaking from a younger generation. But it’s also exciting and gritty, and the entertainment factor will keep us locked into it. It also uses the gorgeous Irish language, which you don’t get to see.”

Keoghan always uses his experience on film sets to learn as much as possible – not just about the film’s subject matter, but whatever life lessons he can accrue from his directors and co-stars. He’s particularly enthusiastic about working with older actors, and values spending time with people like Michael Fassbender and Brendan Gleeson, with whom he acted in the crime drama Trespass Against Us.

“They’re such interesting people, and I learn so much from them – not even about acting, about everything. Michael and Brendan will just be on set talking about Sigmund Freud and I’ll be like ‘Who’s that?’ And they’ll tell me about it and encourage me to look things up. I’m learning from them all the time. Then I’ll watch them do their scenes, and learn so much from that too. I’m much more interested in art now. I feel more open to things.”

Having worked with independent directors like Lance Daly and Bart Layton, as well as such modern visionaries as Christopher Nolan and Yorgos Lanthimos, Keoghan has his eye on writing and directing in the future.

“Working with great people, great filmmakers, you just appreciate how good they are, and you see their love for it and it makes you want to try it. So yeah, I definitely want to try everything.”

In spite of his rapid ascent, Keoghan recognises the power an actor can harness by remaining enigmatic.

“Killian Scott once told me that the more people see you, the less interested they are in you,” he says. “And that made so much sense. You look at Daniel Day Lewis, and he only does films every few years – but when you do see him, your eyes are glued to him. And he’s so different in everything. I don’t feel like I have to rush or take every job – I want to have a great life as well as a great career.”

In those terms, it’s his co-star on The Killing Of A Sacred Deer, Colin Farrell, and Dunkirk co-star Cillian Murphy, who have inspired him the most.

“Colin and Cillian are two genuine family men,” says Keoghan admiringly. “You don’t just learn acting from them, you learn about life, and about what it means to be a good person. That’s what I want.”

Black 47 and American Animals are released respectively on September 5 & 7