In the eyes of opponents, Assad is a murderous autocrat who would do anything to cling to power. The U.S and its allies accuse him of resorting to gassing his own people, a claim the regime denies.
But for his supporters, he is a nationalist hero fighting Western imperialism and ensuring stable, secular rule in a turbulent region wracked by sectarian wars.
Assad himself appears fueled by an unshaking belief that Syria would collapse without him and that he is not crushing a popular rebellion, but fighting an attack by foreign-backed terrorists.
In a televised speech to parliament in June 2012, he likened his crackdown to a doctor trying to save a patient.
"When a surgeon... cuts and cleans and amputates, and the wound bleeds, do we say to him, 'Your hands are stained with blood?"' Assad said. "Or do we thank him for saving the patient?"
The question that has always been debated about Assad is whether he leads his regime or is led by it.
The leadership he inherited was meticulously built by his father, Hafez Assad. The Assad family and its minority Alawite sect held the most sensitive positions in the military and intelligence agencies. But they weren't the only ones: Select families from the Sunni majority and from Christian and other minorities were given powerful posts or economic spheres that invested them in the regime.
Bashar Assad's first months as president after succeeding his father in 2000 ushered in hopes he would loosen his father's iron grip. Even after it became clear he too would not tolerate dissent, he was still portrayed by many as a reformer at heart, fighting against an old guard who restricted his ambitions.
Even some of his strongest critics in the current war once believed he could be a positive factor.
As a senator, US Secretary of State John Kerry visited him repeatedly, dining with Assad and his wife at a restaurant in Old Damascus in 2009. Former French President Nicholas Sarkozy invited him to Bastille Day celebrations in 2008. Even after his forces fired on protesters at the beginning of the uprising against him in March 2011, Hillary Clinton suggested he was different than his father a "reformer" who should be given a chance.
So how did a purported reformer become a leader that Kerry now compares to Adolf Hitler?
"It's like a Greek tragedy," says one Assad biographer, Jean-Marie Quemener, whose book Docteur Bachar, Mister Assad, was published in France in 2011.
"At each step of his existence, he had every chance of choosing the right way. But each time, either the rug was pulled from under him, or he took the wrong decision," he told The Associated Press in Paris. "Each time, his destiny was forced."
Assad came to power by a twist of fate.
The elder Assad was cultivating Bashar's older brother Basil to succeed him. But in 1994 Basil was killed in a speeding car crash in Damascus. Bashar was summoned home from his ophthalmology practice in London, put through military training and elevated to the rank of colonel to establish his credentials so he could one day rule.
When Hafez died in 2000, parliament quickly lowered the presidential age requirement from 40 to 34. Bashar's elevation was sealed by a nationwide referendum, in which he was the only candidate.
"When his father called him, he wasn't ready to take power. He tried to get his younger brother to take his place," said Quemener, referring to Maher Assad, who now heads the powerful Presidential Guard.
"His destiny was forced on him, he never wanted to be leader of Syria."
The Syria that Hafez left his son was molded by 30 years of hidebound rule, with a Soviet-style centralised economy. The hand over dissent was so stifling that Syrians feared even to joke about politics to their friends.
The younger Assad seemed a breath of fresh air.
Lanky with a slight lisp, he had a gentle demeanor. He talked of his love of computers in fact, his only official position before becoming president was head of the Syrian Computer Society. Assad enjoyed listening to Phil Collins and British rock group ELO, Lesch recalls.
His wife, Asma al-Akhras, whom he married several months after taking office, was attractive, stylish and grew up in a west London suburb. The young couple, who eventually had three children, seemed to shun trappings of power. They lived in an apartment in the upscale Malki district of Damascus, as opposed to a palatial mansion like other Arab leaders, and made surprise appearances in public, to the delight of their supporters.
The charming first lady provided a counterpoint to Bashar's geeky demeanor. Together they gave the appearance of a power couple who could bring progressive values to Syria.
One of the young female aides in his presidential office even referred to Assad adoringly as "the Dude," a familiarity inconceivable with his father, according to a purported trove of emails leaked from Bashar and Asma's accounts and made public in late 2011 by London's The Guardian newspaper and WikiLeaks.
Hopes for a political opening dissipated quickly. Early on, Assad reversed a brief loosening of restrictions on political activity. Instead, he opened up the economy. Under free-market reforms, Damascus and other cities saw a flourishing of malls, restaurants and consumer goods. Tourism swelled.
A cousin of Assad, Ribal al-Assad, says he believes Bashar truly intended reforms, including allowing political parties, but was thwarted by the entrenched elite showing how Bashar ultimately relies on the regime core.
"He is not the strongman. How can he be?" Ribal told the AP. "He didn't come up through the military ranks ... He didn't put these people in, his brother did and his father did. He's more afraid of being assassinated by one of them than he is of Western air strikes."
Officials and diplomats who met with Assad speak of a vain man, convinced his was the only right way.
Assad sees himself "as a sort of philosopher-king, the Pericles of Damascus," Maura Connelly, then-US charge d'affaires in Damascus, wrote in a June 2009 secret diplomatic cable, released by WikiLeaks.
Assad's gravest challenge came when small protests erupted in the country's drought-stricken south in March 2011 and spread quickly to other areas, at the time of the "Arab Spring" uprisings.
His response was to use the brutal tactics of his father, hoping to nip the protests in the bud.
Security forces repeatedly opened fire on protesters. But the outrage only caused a snowball effect. As the uprising hemorrhaged into civil war, Assad unleashed his military to blast opposition-held cities, as well as the pro-regime gunmen known as "shabiha," alleged to have carried out mass slayings.
His actions squandered the goodwill of those who still saw him as an instrument of change. Even the first lady was tarnished. The leaked emails showed her splurging on expensive jewelry, bespoke furniture, and a vase worth more than US$4,000 from Harrods department store in London, even as violence engulfed the country.
Assad turned to his own family, but now that circle is dwindling. His younger brother Maher is still by his side but his elder sister, Bushra, a strong voice in his inner circle, is now said to be living in the United Arab Emirates. Her husband, Deputy defence Minister Assef Shawkat, was killed in a Damascus bombing last year. One of his closest confidantes, former elite commander Manaf Tlas, defected.
Quemener said only two people can reason with him at this point: His mother and his wife.
"Like all dictators he's very alone, so he's forced to take decisions, and that tortures him."
-AP
