I grew up 200 miles south of Belfast. Northern Ireland’s grass is the same distinctive green as the fields of the Irish Republic where I spent my childhood. Its dramatic coastline evokes the same feeling as Connemara’s. Belfast has a zone of shiny, modern apartments and offices, the Titanic Quarter, not unlike Dublin’s Docklands. And yet, for all the familiarity, so much about Northern Ireland feels foreign.

It’s not just the Union Jack flags that weave their way over and back across the Shankill Road, 15 minutes’ walk from Belfast’s main shopping street. It’s not the enormous murals of men in balaclavas holding automatic rifles, a sight that still unnerves me. It’s not the practicalities of a different currency, different road signs, different speed limits. It’s more the sense of the place and my feeling of otherness within it.

Northern Ireland’s conflict was the backdrop to the first 15 years of my life. After almost a decade away, I returned in April to cover the riots that erupted when loyalist protests against post-Brexit trading arrangements descended into violence. The unrest lasted more than a week.

On the worst night, a bus was torched and water cannon were deployed for the first time in six years. It was a scary experience, heightened because of the news reports I remember from childhood. Back then, armoured police vans on Belfast’s streets, blazing fires and masked rioters led to outcomes far deadlier than the scenes a few months ago.

This year marks the centenary of the partition of Ireland into an independent south and a north that is part of the UK. Cause for celebration in one community and condemnation in the other. And with Northern Ireland beginning another marching season, when unionists celebrate their traditions with parades and bonfires, the region is bracing again.

Poverty, joblessness and the anxiety and boredom of lockdown all played a part in driving people on to the streets earlier this year. So too the struggle to find Northern Ireland’s place in the UK after Brexit. But something else was going on too, something particular to its involuted past.

For many, the most striking feature of the April riots, from Belfast to Coleraine and Londonderry, also known as Derry, was the extreme youth of those charging police, hurling bottles and rocks and petrol bombs. Some were not yet in their teens. I have spent the past few months asking young people, and the adults who work with them, what they see for the future of the place they call home.

When I drive into a loyalist area, I’m quickly marked out because of the Republic of Ireland plates on my car. Some of the kids I meet delight in sharing their hatred of Catholics. When I ask one group what would make Northern Ireland better, a teenager replies that all the Catholics should be pushed out and their houses burnt down.

There are roads I don’t park on, because the car could be a target for vandals. At one meeting, in an empty building deep in loyalist territory, my interviewee asks me if I have come alone, and I wonder if I shouldn’t have.

The adults I meet tell me that the roots of the recent unrest stretch back far further than the Northern Ireland protocol, the complex post-Brexit agreements that have become the unlikely subject of teenagers’ banners and battle cries.

With that in mind, I travel to one of Northern Ireland’s largest housing estates to meet Nathan Anderson. He was five years old when the 1998 Good Friday Agreement ended more than three decades of sectarian bloodshed. But he can remember the joy and relief in his loyalist Belfast community when family members and neighbours came home from prison, freed from their sentences under the terms of the landmark peace deal. Even as a child who didn’t really understand, he says, “we knew the boys were getting out . . . That was fantastic to see.”

Anderson was part of a promised generation: the first to grow up without the ever-present threat of bombings, shootings and riots that had claimed more than 3,600 lives. Now a 28-year-old single father of two boys, he still lives in the working-class area of Rathcoole that was home to his parents and four brothers. “There was five of us. Four are here — we’ve all got our own houses,” he tells me during a walk round the estate.

Rathcoole, about six miles north of Belfast, is a place of elaborate playgrounds and huge murals celebrating loyalist paramilitary groups. It is a place, says Anderson, where a few minutes’ walk to the local shop can take an hour because of “the people you run into” and where, during annual festivities to celebrate the Protestant victory at the Battle of the Boyne in 1690, children run freely in and out of each other’s open houses. It was also one of the areas where, in April, loyalist protesters clashed with police for more than a week.

As we walk through streets where cars burned, the optimism of 1998 is distant. The Good Friday Agreement ended armed violence between the Protestants, unionists and loyalists who supported Northern Ireland’s union with Great Britain, and the Catholics, nationalists and Republicans fighting for a united Ireland. But the communities remain on opposite sides of a fragile political divide.

“It’s important to understand that peace agreements aren’t fairy stories,” Jonathan Powell, chief of staff to former UK prime minister Tony Blair at the time of the peace deal, told me. “People don’t get to live happily ever after just because you’ve signed a peace agreement anywhere in the world.”

The spark for the spring riots was the fallout from Britain’s exit from the EU, which imposed a customs border with the rest of the UK that unionists see as a threat to their British identity. But the fuel was the deep dissatisfaction of loyalists, who have seen little improvement to their lives from the peace process and believe Catholics have progressed more quickly in education and jobs.

Anderson, who works in manufacturing and has organised community meetings around Brexit’s consequences, is one of the disillusioned. In 2012, protests over the removal of the Union Jack over Belfast’s City Hall turned violent, and he was arrested. Though he says he had no part in the violence, Anderson was convicted and sentenced to eight months for riotous assembly. He was 20.

“Before prison, of course I aimed high — all teenage boys aim high . . . [Now,] in a work sense, I have to aim low,” he says. More violence could have a similar impact on Rathcoole’s young people, who he believes are driven to the streets as he was. “It was patriotic young kids who wanted to do something . . . so that’s just how they went about it,” Anderson says, describing the omnipresent question of identity and culture. “It’s all around you. It’s impossible to get away from: you see it, you hear it, you feel it.”

Every generation in Northern Ireland has taken part in some kind of civil disobedience, he tells me. “It’s like the culture . . . I’m not making it socially acceptable at all. I’m just explaining how easy it is for a community to get involved in, on both sides of the community . . . People just go and watch these things. It just became the norm.”

During the April violence, community leaders and politicians publicly appealed to protesters to “think of your futures”. “What future?” was the response of many working-class teenagers and young adults I spoke to on both sides.

The areas where rioting broke out are some of the country’s most economically deprived. Five of the 10 most deprived communities in Northern Ireland border Belfast’s peace walls, according to a broad deprivation measure used by Northern Ireland’s statistics agency. Scores for income, healthcare and unemployment are particularly bad. “There’s that feeling of always being told, ‘Youse are at the bottom of the line, youse will never achieve this’,” says Alan Waite, co-founder of R-City, a community group created in 2013 to develop skills and opportunities for young Protestants and Catholics.

Around Belfast, youth clubs and community groups have been trying to stop the city’s most vulnerable from being lured into violence. Earlier this year, for example, they loaded kids who were watching the riots on to buses and drove them to their centres and provided pizza and movies. (The gatherings were allowed even under lockdown.)

Such tactics are not always effective. “You’re never going to beat a kid’s adrenaline rush off a riot. You’re not going to stop them,” says Michael Logan, an 18-year-old who works part-time at Townsend Outreach Centre, a youth centre off the loyalist stronghold of the Shankill Road. Yet Logan was among those who went out to attempt to defuse things. He recalls the smell of petrol and the sight of “kids as young as 12 and 13 breaking bricks and stuff off the ground”.

As a young teen, Logan used to attend a sort of fight club. He calls them “sectarian fights”. Groups of teens from both sides would gather for pre-arranged clashes, usually around 50 on each side, though only 10 to 20 would actually fight, while the others watched. “At the start, it was just a game of chase. One side would run at the other, the other side would run back . . . but it started to get very dangerous,” he says.

Logan recalls the last night he went to one of the fights, when a young nationalist boy was beaten so badly he required intensive care in hospital. “The screams . . . ” he says in a low voice, looking into the middle distance of the industrial kitchen we’re chatting in. He never returned.

He believes the glorified violence of Northern Ireland’s past was a big factor driving kids on to the streets recently. “They want to look up. They see their fathers and their grandfathers, their uncles who all fought in these paramilitaries, but they fought for a cause.” That cause is no longer there, he says, but the feeling that no one is listening endures.

Paramilitary groups on both sides continue to exert control over communities to this day, according to the latest dispatch from the Independent Reporting Commission set up by the UK and Irish governments, and are believed to have been involved in the background of April’s riot, though Winston Irvine, a former (Protestant paramilitary) Ulster Volunteer Force boss turned community worker, says the paramilitary angle is “way overblown”.

Ruth Petticrew, 59, a former deacon in the Presbyterian Church, came to Belfast in her mid-twenties and has been running Townsend Outreach Centre for 30 years. Working on the frontline of communities during the Troubles was “horrendous”, she says. “I look back and think I don’t know I survived.”

Once, after agreeing to officiate at the funeral of a murdered 21-year-old, she received death threats from the loyalist Ulster Defence Association paramilitary group. She says she refused to back down, requesting only that if they were going to kill her, they “don’t do it in front of young people [at the centre] because they’ll never forget it”.

Many of the challenges are mirrored in inner-city Catholic communities. Stephen Hughes says he inherited “nine kids and a chair” eight years ago when he took on the job of running St Peter’s Immaculata youth centre near the Lower Falls Road, one of Belfast’s most deprived Republican areas. Today the centre is used by 50 to 100 boys and girls six nights a week who gather to watch football, play computer games, colour in pictures and chase each other round. “It takes you away from stuff on the outside,” says Sean, a 13-year-old who wants to be an engineer. By “stuff” he means “all them riots and all that happened”.

Hughes, a 55-year-old bear of a man who laughs as loudly with the kids as he shouts when disciplining them, speaks about his charges with fatherly pride. Children can be suspended for misbehaviour but never expelled, he tells me. Hughes hopes this unconditional welcome — and personal development programmes that cover everything from how to brush your teeth to table manners — can alleviate the damaging cycle some families are trapped in. “It’s very, very easy for that to become all-consuming,” he says.

One night last month, as he and I drove between his centre and Petticrew’s, we spotted a fire on a strip of grass between blocks of houses. By the time the fire engines were approaching, Hughes was on the phone trying to get a colleague to come and help stop the kids confronting the firefighters.

More than a month ago, loyalists began building the towering structures that they will burn on July 11. Setting them on fire ushers in the main event in Ulster’s marching season and is intended to commemorate the 17th-century battle that initiated the ascendancy of Protestants in Ireland. Eleventh Night bonfires are typically accompanied by marching bands and parties.

Some of the bonfire builders talk about the season in terms of learning skills such as team building, construction and organisation. They talk about the bonds forged over door-to-door calls to raise funds for materials to construct “the bonnie” and sleeping next to it overnight to defend it. They also talk about burning Republican paramilitary flags. Some events have sparked sectarian violence as well as clashes with the police.

In one of Belfast’s most deprived areas, four boys between the ages of 15 and 21 take a break from gathering fuel for their neighbourhood’s bonfires. When I ask them why so many young people took to the streets, all of them ask not to be named. “They should put the border where it’s supposed to be,” says the youngest. It’s “supposed to be” between the Republic and Northern Ireland. Also, people should respect and understand that “we’re British”, he adds. In this city, says another, “you have to be violent to be heard”.

The sense of voicelessness hasn’t always been this acute. Donna McCracken, who used to run the Black Mountain Action Group in a loyalist area of Belfast and now works there part-time, says there was an “extreme change in attitudes in communities” after the flags protests in 2012-13, as people became more attuned to how their community was being marginalised and disadvantaged.

Protestants held the bulk of the region’s land, wealth, jobs and power when Northern Ireland was created. Between 2001 and 2017, they lost more than 21,500 jobs, while Catholics gained more than 56,000, according to data from the North’s equality commission, highlighting the gulf in the two communities’ experiences since the Good Friday Agreement promised equal opportunities.

Protestants also feel the Police Service of Northern Ireland, created in 2001 to replace the Royal Ulster Constabulary, is more lenient towards Catholics, a perception furthered by the force’s failure to prevent thousands of Republicans from attending the funeral last June of Bobby Storey, a senior Irish Republican Army figure, in defiance of Covid guidelines. A subsequent failure to prosecute attendees, including nationalist political party Sinn Féin’s Northern Ireland head Michelle O’Neill, provoked outrage.

The perceived slights are heightened by loyalist fears that, once the 2021 census is counted, Protestants, who accounted for more than 62 per cent of Northern Ireland’s population in 1926, could be overtaken by Catholics as the region’s largest denomination. That is a particularly alarming prospect as Sinn Féin escalates calls for a referendum on uniting Northern Ireland with the Republic.

“I really understand how Catholics were treated in Belfast and Northern Ireland — it was horrific,” says Paula Robinson, 33, who attended Black Mountain as a teenager and now runs the group. “But putting the Protestant community down and doing the same thing isn’t the answer. That’s not equality.”

The divides between Catholics and Protestants are at the root of most of Northern Ireland’s challenges. Education is supposed to boost equality but instead amplifies segregation, dividing children from a young age, feeding fears and suspicions. Some believe the failures of the educational system have increased the lure of paramilitary groups. “When their aspirations are so low and when their opportunities are very limited, it can be very difficult for people not to buy into that [criminal] lifestyle,” says Hughes.

The system also exacerbates inequality — Northern Ireland sends eight times as many students per head as England to state-funded grammar schools based on entrance exams that favour well-off students, who can get tutoring or other support.

The result is an education system that produces better A-level and GCSE results than in England and Wales but also has “pockets of underachievement” which, according to Northern Ireland’s recently departed education minister Peter Weir, are linked to Northern Ireland’s “divided society”. Young people from middle-class families have reported knowing almost no one outside their own community before they went to university, with some citing Northern Ireland’s divisions as one reason they will make their adult lives elsewhere, fuelling the brain drain that already afflicts the region.

With integrated schools slow to take off, youth groups try to bridge the gap. R-City came about when its founders realised how much common ground their loyalist and nationalist working-class youth groups had, and thought their goals could better be pursued together. The Catholic St Peter’s centre and the Protestant Townsend centre also regularly run joint projects.

Logan credits a youth trip to the US in summer 2019 with members of St Peter’s as changing his view “on the other side as a whole”. He went there apprehensive, “partly because of the stories you hear growing up, things like the IRA — they put the fear into you in case that’s what they’re still like”.

He tells me that on the trip he found Catholics were “very similar” to him and they got on very well. When they returned home, they were asked to his youth club and he to theirs. Yet in Belfast hanging out on each other’s territory poses challenges not found in most places. The clubs are a few hundred metres apart. But once the peace gates separating the two communities are closed in the evenings, they are a 10-minute drive apart.

As Logan explains: “It’s hard getting in and out. I wouldn’t feel safe travelling over there, especially in the daytime. I’d be more scared because I’d be more easily seen.” He believes he would be recognised because “everyone sort of knows each other”, especially with social media.

Faced with such obstacles, new friendships can quickly falter, and have for years. Logan’s mother went on a similar trip to the US as a youngster and made Catholic friends, but her son still grew up fearing the other side. Northern Ireland is rich with these sorts of regular reminders that people have to live in the world as it is rather than the one they might wish for.

Laura Noonan is the FT’s Ireland correspondent

Follow on Twitter to find out about our latest stories first.