It is the summer solstice in New York and Mr Christian Slater is tucked away at the back of a French bistro on the Upper West Side, contemplating cool. “What is cool now?” he says, askance, the famous bat-wing eyebrows arched in thought.

During the late 1980s and early 1990s, when Mr Slater’s star was arcing brightly across Hollywood, cool was disaffected teenagers, irony, bad grades, good smokes and maybe a skateboard. “Cool was anarchy,” he says. “Rebellion.” Back then, and for much of his adolescence and early adulthood, being cool was being in possession of an energy that threatened the establishment’s status quo. Cool was menacing, at least to your parents, and Mr Slater was its ultimate embodiment. “There was an unpredictability that, to a certain degree, people were projecting on me and which, to a certain degree, I wanted to maintain,” he says. “There was a danger.”

In an incredible run of films that began with Heathers (1988) – which celebrates its 30th anniversary this year – a cultish satire in which he played a high-school killer, the actor became a sort of avatar of youthful isolation, angst and violence. As his celebrity grew with the skateboarding classic Gleaming The Cube (1989), pirate-radio story Pump Up The Volume (1990) and the modern Bonnie and Clyde fable True Romance (1993), Mr Slater’s personal life, too, began to colour with the bruised emotions brought on by disorder, confusion and loss – as well as drink, drugs and the other accessories then included in the Hollywood bad-boy kit.

“That’s life,” he says. “Or at least, that’s my life. I definitely spent a lot of time beating myself up, living with useless emotion, guilt and shame. Feeling tortured, and justifying that because the examples I had were other tortured actors. You put that on yourself and think that’s how you’re supposed to behave. There was a level of imitation going on.”

This imitation, he says, was an attempt to find himself, on screen and off. Perhaps it is too convenient, in retrospect, to wonder if we – cinema-goers and writers of profile pieces – were attempting to fit Mr Slater’s real, unscripted life into the narratives acted out by his characters. Perhaps Mr Slater himself was a little too deep in the role that Hollywood had established for him, and continued to play it even when he was off-camera. When, finally, that role became unsustainable, Mr Slater went off the map. Or is that, too, a kind of media-made meta-narrative? “I was still working,” he says, like, c’mon. “I was still trying to get jobs to feed my family. Maybe the work I was doing was under the radar. But there was certainly a point in my life where I lost track of why I was doing it. I was never really feeling completely fulfilled in who I was.” Mr Slater describes a moment during this time, when he was living in a gated community in Miami with his wife, thinking, as the doors closed between them and the world, “Well, that’s it. That’s the end of this life.”

But then he came back, back to his hometown of New York, where his wife, Ms Brittany Lopez Slater, had got a job as head of international exhibitions at Phillips auction house, and back to the public eye with his role on the show Mr Robot, the fourth season of which arrives later this year. This time around, Mr Slater says, he embraced the opportunities with graciousness and glee. “I think eventually you do get to a point where you just say, ‘God, what a waste of energy.’ It’s so damn exhausting. I mean, I remember somebody coming up to me and asking for a photo at a restaurant and I gave him attitude. Then that pissed them off. And then I got scared. I thought, man, it’s just so much nicer to be gracious. I didn’t give up. I stuck with it. I came back and I started to understand what a gift it is to be able to escape and put on the shoes of somebody else. That’s something not to be taken for granted. I keep learning each and every day. And try to show up for things with as much of a smile as I possibly can.”

Mr Slater has changed a lot since the days when he was playing teenage miscreants – he catches himself repeating the word “evolved” – but Hollywood can’t quite let him move on from playing menaces, chaos incarnate. As the titular character on Mr Robot, Mr Slater plays a kind of Shakespearean ghost for the hacker age, the deceased father of Mr Rami Malek’s character, urging on the destruction of the current world order. And in his new film, The Wife, based on the novel by Ms Meg Wolitzer, Mr Slater plays a would-be biographer of a Nobel laureate novelist (Mr Jonathan Pryce) who brings all the skeletons out of the cupboard for the writer’s wife (Ms Glenn Close).

And that all still slaps. That raspy Rasputin’s charm of his, egging everyone on to do their worst, is as powerful as ever. But it’s not everything for the actor who is, if anything, more ambitious than he’s ever been, more open and adventurous, trying everything, anything. Earlier in the day he hosted an episode of Good Morning America, “something I never thought I would be comfortable doing”, he says. “But I do seem to enjoy it. It’s like kind of working at your own private island. Because everybody comes to you. Ethan Hawke came by today. He has a movie that he directed, won a lot of awards at Sundance. And he said, ‘Hey. We met a long time ago.’ And I was like, ‘Really? I don’t remember.’ He was about 14, auditioning for this movie. And I guess I was the reader, the guy off-camera. I was 15. My mother must have been involved because she’s a casting director. He said that I was very cool, smoking a cigarette off-camera. I helped to put him at ease.” Mr Slater laughs like someone who cannot believe their luck.

“I think, as you get older, you get a bit more settled into who it is you want to be,” he says. “So when I get behind the closed door of my house, I have my chores. I do the dishes. I take the garbage out. I have my responsibilities. I show up for my kids. I try to be the best husband that I can be. I try to be a good, open, communicative partner. And at work, I choose to focus on people who take the work seriously, but don’t take themselves seriously.”

Back in the French bistro, the lunch rush is dying down. At 48, Mr Slater is, by about 30 years, the youngest person in the place, but he’s at ease in here, clearly. And he’s at ease with himself. So, here’s the verdict: “I guess what I think is cool now is being open-minded, accepting of other people, what they’re into, who they want to be, what they want to do,” he says. “It’s important. Get involved. Contribute. Give back. I get more energy for being polite and open. Don’t you? I think it makes you feel better.”

And, what, really, could be cooler than that?