Lebanon is hosting around a million refugees from the conflict in Syria, which means that one in four people in the country are Syrian. But the impact on Syria's neighbour goes well beyond a humanitarian crisis, writes the BBC's Kim Ghattas.
The pictures of Hezbollah's martyrs hang from the lampposts and balcony railings. They are plastered on walls and car windshields.
The men died not fighting Israel - Hezbollah's arch enemy - but supporting the forces of its ally President Bashar al-Assad, across the border in Syria.
The southern suburbs of Beirut, a predominantly Shia area, are Hezbollah's support base.
The area is often referred to as a ''stronghold'' of the radical Shia Islamist militant group.
The term conjures up images of dark alleys and military installations, devoid of civilian life.
But it is more of a middle-class suburb, bustling with traffic, cafes and shops, with expensive cars parked outside buildings. Women clad in black veils or in tight jeans and bands of teenagers walk around.
But Hezbollah is feeling nervous about security these days and they are in charge here.
Gun-toting men in black are manning check-points at every entrance to the area.
They guard buildings containing Hezbollah offices, stop people from parking on the street and question anyone who looks like an outsider.
The party is paying the price for its role fighting to support Mr Assad across the border.
Militant groups linked to al-Qaeda have taken revenge and several bombings have rocked this area, killing civilians in the last few months.
One of them was 17-year-old Ali Khadra. He was on his way to the pharmacy after lunch on 2 January when a green Jeep packed with explosives parked along his route exploded, two blocks from his house.
His mother Hanane and brother Mohammed agree to talk to me just days after the tragedy hit their family. The meeting is arranged by Hezbollah's media office.
In the hushed silence of a house in mourning, Hanane tells me she is not angry but felt her heart burning from the loss of her son.
"Everybody in the family liked him. And he was always a forgiving son - calm, friendly and loved," she says of Ali, who had wanted to become an engineer.
Hanane blames radical Sunni groups for killing her son, but I know there was tension in the community because of Hezbollah's role in Syria, so I ask her if this would have happened if the party was not fighting there.
Hanane's response is emphatic. Hezbollah is not to blame, radical Sunnis long had their eyes on Lebanon and they started this, she says.
She is keen to stress that she has nothing against Sunnis, telling me how the first phone-call of condolences she got was from the mother of a young Sunni who had been killed a few weeks earlier in another car bombing.
The Sunni radicals - known as "takfiris", or those who see other Muslims as non-believers - are a threat to Sunnis, Christians and Shia alike, Hanane adds.
'Battle against Hezbollah'
But for Hezbollah, the fight alongside President Assad is also a fight for its own survival.
Syria occupied Lebanon from 1976 until 2005, so it still has key allies here and sworn enemies. That is why every faction, every community in Lebanon feels that its own future is tied to the outcome of the war next door.
In Tripoli, an hour to the north, searing memories of Syria's are still vivid.
In the mid-1980s, the predominantly Sunni city witnessed a ruthless crackdown by Syrian armed forces on Islamist groups.
Dozens of people were killed in what residents describe as a massacre. Dozens if not hundreds more were detained and spent years in jail.
For years under occupation the wounds festered silently. Today, the past drives some of those who cross the border to fight pro-Assad forces.
A local Salafist sheikh, Nabil Rahim, arranged for me to meet two men who have taken up arms.
Wearing jeans, T-shirts and casual jackets, both slightly red-haired and sporting beards, they have day jobs - plumber and night guard at a hospital.
Abu Mujahed - a nom de guerre - is just over 30 years old, and a father of two. He went to fight alongside the rebels in Syria several times in 2012.
Abu Huraira, 26, is taking a break from the fighting to spend time at home with his newborn baby.
His wife is Syrian, from Aleppo, and her father is a rebel commander, so his family fully supports his decision to fight against President Assad.
Abu Huraira was injured in a battle that turned out to be a turning point in the Syrian war last May.
The town of Qusair, close to both the Lebanese border and the central Syrian city of Homs, was strategically important for both the Syrian rebels and government.
Hezbollah poured in hundreds of fighters in a bid to capture it, the rebels lost and Mr Assad's forces regained the upper hand in the conflict.
Abu Huraira sees the Syrian conflict as a battle against Hezbollah and Iran, not just the Syrian president, whom he considers a puppet of Tehran.
He has little hope for Lebanon's future as long as the war goes on in Syria. But he wants a victory for the rebels or he says the war could transfer to Lebanon and become a fight against Hezbollah here.
The fighting has long spilled over into Lebanon.
Almost every week in Tripoli, there are clashes between Sunni militants who oppose Assad in the Bab al-Tabbana district, and pro-Assad militants just up the hill in Jabal Muhsin, an area inhabited mainly by members of the Alawite sect, to which the Syrian leader belongs.
I met a local journalist, Ibrahim Chalhoub, who took us around the city on a quiet day.
We stood on Syria Street, which Ibrahim described as the "demarcation line" between the Bab al-Tabbana and Jabal Muhsin.
The area is poor, like a slum, the buildings are so run down that it is hard to tell if the pockmarks are from recent fighting or past wars.
"Sometimes I don't recognise it as my city anymore," says Mr Chalhoub. "Sometimes I feel it's no longer Tripoli or Lebanon. Sometimes I feel like I am in Syria."
Mr Chalhoub, a Christian, is losing hope for the future.
For the first two years of the Arab uprisings, Lebanon seemed a haven of calm. But no-one expected the uprising and the war in Syria to last this long.
The spillover became inevitable and the more it drags on the harder it will become for Lebanon to withstand the shockwaves, and resist the descent into chaos.
'Room for hope'
Back in Beirut, I meet Ronnie Shatah, the son of Mohammed Shatah, a soft-spoken former finance minister who was assassinated in December 2013.
He had been a key political advisor to Saad Hariri, the leader of the March 14 political bloc that opposes Syria's government.
Mr Hariri's father Rafik, a former prime minister, was assassinated in 2005 - a killing that led to the Syrian withdrawal and for which four alleged associates of Hezbollah are being tried in absentia by a UN-backed tribunal at The Hague.
Ronnie Shatah, 32, with light eyes and a big mane of red hair, used to give tours of Beirut to tourists, Lebanese emigres visiting their home country. He believed in a city that brought everyone, of all faiths together. But his outlook has irremediably changed.
"I still care deeply but the Beirut that I loved took my father, it took my anchor, it took also my best friend, my mentor and now I'm not sure if I want to stay," he says as we sit on the seaside promenade.
"There is room for hope if the Lebanese take on the challenge of reflection. Otherwise, it's perpetual chaos."
His father was buried in a central square in Beirut on 29 December. That same evening rooftop clubs in nearby buildings were packed - the music does not stop in Beirut. But Mr Shatah is happy that people still have the appetite for simple pleasures of life.
"That people are dancing next to my father's grave doesn't bother me," he explains. "But what bothers me is digesting the abnormal state of affairs, being unwilling to confront the problems head on to avoid the next assassination. We're dancing into the abyss."