The biggest new thing in hip hop is smaller than you expect. Backstage with his entourage at Vicar St., Kendrick Lamar passes almost unnoticed. He has the semi-stoop of someone happy to blend into the background, speaks softly, avoids eye-contact. If you didn’t recognise his face from a zillion photo-spreads you could easily forget he was there.

Of course you do recognise his face because this is Kendrick Lamar, dubbed the ‘Bob Dylan of rap’ by Pharrell Williams, the ‘new leader of the west coast’ by Snoop Dogg. The rhymer who, with zero marketing, outsold Rihanna when their two albums went head to head over the summer, he doesn’t need to cast a shadow or have anyone make a fuss. That would be showing off. It’s beneath him.

As, it initially appears, is chinwagging with the media. Hot Press is cooling its heels, wondering when/if we’re going to have some quality time with Kendrick. He and his crew were AWOL most of the afternoon and are now sitting down to Piri Piri chicken take-out. Stage time is imminent. There’s this sinking sensation journalists get when it starts to look like a promised interview isn’t going to pan out. Hot Press has had it for the past hour.

The queasiness recedes as Lamar ambles over and proffers a hand. A minder in tow, we’re bundled into a dressing-room in the bowels of the building. Lamar pulls up a stool, Hot Press hunkers by the table. Because we’re standing and he’s sitting, his lack of height is accentuated. It’s like you’re talking to a 12-year-old – a feeling exacerbated by his soft voice and a demeanor that, one-on-one, comes off as impressively guileless.

The same quality infuses his hit LP good kid, m.A.A.d city. A stream of consciousness concept album, good kid chronicles a day in the life of Lamar as he wanders his ghettoised hometown of Compton, the sprawling, crime-raddled suburb of Los Angeles. He has run-ins with gang-bangers, buys drugs, breaks up with his girlfriend, is harassed by the police. It’s the raw material of a hundred workaday rap records – what’s different is the way Lamar lets his self-doubt and vulnerably shine through. He doesn’t lionise Compton, nor does he condemn it. He just shows you what it’s like to live there.

“I want to bring a different perspective,” he resumes. “Plenty of people have rapped about Compton. I want to show the other side of the story, talk about the kid trying to escape temptation rather than avoid it.”

Growing up in Compton, Lamar was in the apparently unusual situation of having a father. Most of his friends were in one-parent families, their old men – or some of them at least – doing 25 to life in San Quentin. This gave him an outsider perspective. He saw Compton the way an outsider might.

“I was the only kid in my neighborhood with a dad,” he says. “All my homeboys, they live with their grandmothers. Because everyone was involved in gangs, their dads were behind bars. And, in the ‘80s, the crack epidemic went crazy. So all the mothers got strung out on drugs. There was nobody else to look after them.”

He was not completely untouched by gang culture. His father had his ‘wild crazy’ moments and was a gun enthusiast. Lamar’s uncles, meanwhile, were deeply involved with the Crips. As a teenager Lamar worshiped the older men and was drawn to their lifestyle, a blur of drugs, guns and honeys. He was very nearly sucked in.

“You are going to look up to your uncles. Hell, they didn’t even feel like my uncles – they treated me like a younger brother. It was easy for me to be influenced. I bumped my head a few times, got close to being involved [in gang culture] in a serious way.”

He vividly recalls the day he decided he wanted to be a rapper. He was eight and word got out Dr. Dre and 2Pac were shooting the video for ‘California Love’ two blocks from his house. His dad took him to watch.

“Luckily, I had a father right there for me. He was from the street, knew how things worked. I had a little more insight than the homeboys. In the end I wanted to do something positive, not continue the cycle. Music was my way out.”

He sits forward, warming to the topic.

“My family moved to LA from Chicago. If you think Chicago is bad now, well it was even worse then. So they thought, ‘Yeah – California’. Of course, they didn’t end up in the Valley, they ended up in Compton. My uncles were 10, 11 at the time. That’s the age you’re sucked into the gang lifestyle. They got influenced by the Crips. Two of my uncles are still in prison. Another recently got out. It’s good to show him what I’ve achieved, to show him you have a choice and that you can escape that life.”

Compton’s place in the history of rap is richly documented – bizarrely, it’s also home to Los Angeles’ only cricket team, Compton Cricket Club. The city was namechecked on NWA’s 1988 gangsta opus Straight Outta Compton and by groups such as Compton’s Most Wanted (their 2006 LP was actually called Music To Gang Bang). Rappers have inevitably portrayed it as a community under siege, from drug dealers, gangs, the police. Did Lamar want to redress the balance? Depict Compton as a place where real people lived real lives?

“That’s what was selling records at the time,” he says of earlier projects inspired by Compton. “Once a label figures what is selling, well you’re going to see more artists doing that. My whole aim was to take the culture back to its essence. That said, all of those artists you mentioned were people I grew listening to. I won’t sit here and tell you I was listening to stuff from the East Coast. It was all West Coast. I had to catch up, later on, with guys like Biggie, Jay-Z, Nas.”

Kendrick was catching up with them just as they were catching up with him. What about the extravagant praise? When Pharrell is comparing you to Bob Dylan it’s got to be difficult not to have your head turned.

“It’s flattering, feels great,” he acknowledges. “But, you know, this didn’t happen overnight. I studied my heroes, tried to identify what made them a great artist or a great songwriter. And then I applied what I learned. It was hard work. A lot of hard work.”

He started out flogging mix-tapes on street corners. Soon he was filling local venues. Then rooms in New York. For an unsigned West Coast rapper to be storming the East Coast was, he tells you, phenomenal. Labels began sniffing around, Dr. Dre – another Compton native – invited Lamar to hang at the studio. An accomplished musician, Lamar didn’t take Dre up on his offer of production assistance, but he did invite him to come rhyme with him on good kid (he pops up on bonus track, ‘The Recipe’).

Lamar appears grounded, lacking the standard issue rapper ego. As his fame escalates – he will, you suspect, soon be performing in arenas – does he worry about being able to keep it together? Hip hop is notorious for breeding narcissists. With a whole world of temptation about to be laid at his door, how will he respond?

“The best thing I can do every morning is wake up and look in the mirror – stare at myself deep in the eyes,” he says, tapping the side of his head with an index finger. “Those are the same eyes I’ve been looking at all my life. That’s how I’ll keep it together.”

He tells an amusing story about being courted by Jay-Z, almost a decade ago. Still in school, he was winning rap contests in LA, building local buzz. The then-boss of Def Jam Records, Jay-Z flew Lamar to New York for a development confab. Nothing came of it and he hasn’t laid eyes on Jay-Z since. They next time they cross paths he imagines things panning out differently.

“He didn’t really follow through,” says Lamar, smiling. “I’d love to meet him again. Just to see if he remembers.”