The flame of revolt that first flared in Tunisia, previously one of the Arab world's quietest corners, consumed autocrats there, in neighbouring Egypt and, more violently, in Libya.
Contained in Bahrain, it flickered on in Yemen where in time a veteran leader was pushed aside. In Syria, it is still being fiercely fought over. All Arab countries have felt the heat.
Gritty political transitions are under way in nations where "revolution" has triumphed, ushering in contests over power, identity and religion, continued economic and social malaise, new opportunities for Islamist radicals, lawlessness and a surge in sexual violence against women that has gained publicity.
Among a host of unintended consequences is an outflow of weapons and fighters from Libya after the overthrow of Muammar Gaddafi that has helped to destabilise neighbouring Mali.
Another is rising tension between Sunni and Shi'ite Muslims across a region already buffeted by rivalry between Shi'ite Iran and U.S.-aligned Sunni powers led by Saudi Arabia.
In Bahrain, the Saudis helped to crush protests led by the Shi'ite majority, and in Syria, mainly Sunni rebels are battling Iran's principal Arab ally, President Bashar al-Assad, whose rule is built around his Shi'ite-rooted Alawite minority.
Many Arabs are proud of their new freedom to speak out and to take to the streets against real and perceived wrongs, but it has proved trickier than many expected to create prosperity, fill power vacuums left by entrenched rulers and convert police states into stable democracies governed by the rule of law.
"WORK AND DIGNITY"
Unemployment, poverty and rising prices, which helped to fuel the revolts in Tunisia and Egypt, remain grievances in economies hit by unrest that has deterred tourists and foreign investors.
"Our basic demand was work and dignity, but now under the Islamists we don't have either," said Aymen Ben Slimane, an unemployed young man in the Tunisian capital. "We have no confidence in them to achieve the goals of our revolution."
Last week's assassination of opposition politician Chokri Belaid plunged Tunisia into its worst crisis since the uprising and raised fears of violence in a country where an Islamist-led government faces strong liberal and secular opposition.
Zouhour Layouni, a 22-year-old student in a headscarf, said Tunisia had won freedom of expression and could accommodate differences between Islamists like her and their opponents.
"The assassination of Belaid is an exception," she said. "Now we ask secular people to give us time and they will see the results. Our hope is that Tunisia will be united."
Tunisia's troubles and those of other Arab nations in early stages of transition should come as no surprise.
"These revolutions require a long-term perspective. It would have been unrealistic to think that in two years these countries would have transformed themselves into perfectly functioning democracies," said Eric Goldstein of Human Rights Watch.
"It's important not to underestimate how much 25 years of dictatorship and the politics of fear and intimidation have distorted the political landscape," he said, adding that Tunisian political parties lacked experience in negotiating their differences peacefully. "They are learning as they go."
Well-organised Islamist groups such as Egypt's Muslim Brotherhood and Tunisia's Ennahda party have won elections after revolts they did not start, but after years of preaching that "Islam is the solution" both have collided with the complexity of managing modern economies and governing unruly societies.
"People are angry because they feel the revolution did not change their lives," Ennahda's leader Rached Ghannouchi told Reuters this week, acknowledging how hard it is to meet popular expectations raised by the overthrow of Zine al-Abidine Ben Ali.
Relatively moderate Islamist parties face pressure from ultra-orthodox Salafis, whose drive to write stricter codes into new constitutions and laws dismays their liberal opponents.
Some Salafis, but by no means all, are ready to pursue their goals through violence. The attacks on U.S. diplomatic missions in Tunis, Cairo and Benghazi in September, following an anti-Islam video that surfaced in America, illustrated the danger.
A smattering of Arab voices reflecting on the ferment of the last two years provides individual insights, even if they cannot encompass the complexity of changes in the Middle East that will take years, if not decades, to shake down.
In Egypt, liberal activist Abdelrahman Mansour, who helped organise protests on Jan. 25, 2011 that snowballed into an uprising against Hosni Mubarak, said Islamists had failed to bring Mubarak-era officials to account or to establish a real democratic transition after an interim period of military rule.
"Instead, Islamists staged a series of power grabs that marginalised other political forces," he said, arguing that the military and their Islamist successors had sidelined youth groups and others who had prepared plans for reform of the interior ministry, judiciary and other state institutions.
"Their aim was to contain the revolution and its youth by convincing the average Egyptian citizen that the youth were the ones destroying the revolution, not the ones who ignited it."
Samir Wisamee, an Islamist activist, said Mubarak's removal and the holding of free and fair elections were major gains, but also lamented "the lack of accountability within the Interior Ministry and the cycle of violence that plagues the country".
While hundreds of people have died in unrest in post-Mubarak Egypt, the violence is dwarfed by that in Syria, where the United Nations says nearly 70,000 have now been killed since a revolt against Assad began with peaceful protests in March 2011.
Syrian opposition campaigner Fawaz Tello, now in exile, said he was saddened by the human cost of freedom extracted by Assad's "savage" ruling system and by international inaction.
But his biggest disappointment was a Syrian opposition that he said lacked leadership, political acumen and administrative skill. "It has not managed to connect effectively with the spirit of the revolution and it is responsible for corrupting the revolt by trying to buy loyalties of the rebels," he said.
"But I'm proud that a defenceless people who have challenged a totalitarian system that has been strengthening itself for the last half a century are on their way to victory," Tello said.
After so much carnage, the outcome of Syria's conflict is far from clear. Nor can anyone be sure what will emerge in other countries where Arabs rose up for freedom and dignity.
Nathan Brown, at the Carnegie Endowment for International Peace, said the uprisings expressed "disgust in the prevailing political order and a hope that if societies could just get their politics right they would solve their pressing problems".
Structures that kept self-serving Arab leaders in power had been toppled, "but there was no systematic thought about what should positively replace these systems, and building good ones has been far harder than anticipated", he said.
"The biggest obstacle to such a process in Egypt and Tunisia - the two most hopeful countries two years ago - has not been the act