Louai Faisal, 27, a Palestinian resident of this West Bank city long considered a Hamas stronghold, has spent three periods in Israeli prisons, starting in 2003 when he was sentenced to two and a half years as a would-be suicide bomber for Hamas.

More recently, he has spent three terms in Palestinian Authority prisons in the West Bank, arrested each time by a different security apparatus, he said, and interrogated because he was suspected of belonging to Hamas. The latest detention lasted six weeks and ended in March.

Mr. Faisal said he was never tortured in Israel, only in the Palestinian Authority prisons, where the treatment, he said, was “much worse.”

This week, a reconciliation pact was signed in Cairo by the leaders of the rival Palestinian factions — Hamas, the Islamic militant group that governs Gaza, and Fatah, the mainstream secularist party led by Mahmoud Abbas, the president of the Palestinian Authority, whose security forces operate in the West Bank.

Human rights groups have reported detentions, torture and abuse of political opponents by both sides in recent years, underlining the obvious difficulty in turning bitter enemies into political partners overnight.

Asked if he could forgive his Palestinian jailers, Mr. Faisal, who works as a florist, using skills he learned in Israeli prisons, said: “It is hard for me. I have suffered. It will be up to God to help.”

The unity deal is intended, among other things, to strengthen the Palestinian leadership that is pursuing recognition for a Palestinian state — not half a state or two separate states — at the United Nations in September. But the quest for unity has exposed a fractured society that remains geographically separated and still largely controlled by Israel.

Palestinian independents who helped mediate between Fatah and Hamas say that the recent upheavals in the region and other factors have led Hamas, which is considered a terrorist organization by much of the West, to become more pragmatic.

“If I read history carefully,” said Mahdi Abdul Hadi, a Palestinian analyst and one of the independent mediators, “this is the end of an era and a new beginning for Palestine.”

Many Palestinians said they hoped this was the case, but they were far from convinced that the two parties could put the past behind them and share authority on the ground.

The simmering rivalry between Hamas and Fatah worsened after Hamas won parliamentary elections in 2006. It turned into a deep schism a year later, when Hamas routed the pro-Abbas forces in Gaza after a brief but bloody factional war.

The preliminary deal that was signed on Wednesday essentially leaves the rival forces in control of their respective areas until joint committees can work out formulas for sharing government functions and security control.

“Personally, I do not believe there will be healing,” said Dr. Khaled al-Hilo, the director of a clinic in the Amari refugee camp, abutting the city of Ramallah, where the Palestinian Authority has its headquarters in the West Bank. “They have two different visions.”

In the alleyways of the camp, which looks today like a poor neighborhood of the city, Fatah is still popular. This week, residents of the camp recalled the anger they felt when Hamas took over Gaza.

“If someone slaps you in the face, you will never forget that,” said Ali Hussein, 67, who became a refugee with his family when Israel was established in 1948. His original home was in Malha, which is now an upscale Jewish neighborhood of West Jerusalem. Referring to the Palestinian infighting, he noted, “People here said, ‘If you are so powerful, fight to liberate our land first and then fight with each other.’ ”

One of Mr. Hussein’s sons was paralyzed by an Israeli soldier’s bullet during the first Palestinian uprising in the late 1980s. Another son, Abed, 25, was recently released from an Israeli jail, where he served two and a half years for dealing weapons for Fatah.

After the West Bank-Gaza split, said Abed Hussein, Hamas asked for its prisoners to be separated from the Fatah inmates in the Israeli jails.

In the West Bank, Hamas activists were maintaining a low profile this week, uncertain of what lay ahead. Even if they were no longer at risk of arrest by the Palestinian Authority, there was still the risk of being arrested by Israel.

“We have become accustomed to this,” said Aziz Dweik, the Hamas speaker of the Palestinian parliament, long defunct, that is supposed to be revived under the new accord. Mr. Dweik was himself released from an Israeli prison in 2009 after serving nearly three years for belonging to an illegal organization.

Mr. Dweik, a resident of Hebron, added that he was “very concerned about the two parties who rejected the reconciliation agreement: the occupation, which can do what it wants, and the United States, which also expressed concern.”

But he said of the Palestinians, “United we stand, divided we fall.”

Muhammad Nasser, a retired Fatah fighter who lives in Ramallah, came from Baghdad to the Palestinian territories in the mid-1990s with the Palestinian leader Yasir Arafat.

“We are one family,” he said. “In the same family, you have Hamas and Fatah.”