One a murderous smuggler, the other the ruthless heir apparent, both of Saddam Hussein's sons were vital cogs in their father's terror machine.
Uday, the dictator's oldest son, who has died aged 39, was a flamboyant character at one time thought of as his father's successor. But his erratic and violent behaviour soon dispelled these thoughts, even if he did manage to carve out for himself a distinctive and feared place in Iraq's clannish political world.
Uday was 15 when his father became president of Iraq in 1979. He later claimed that his father had taken him to watch some of the executions of disgraced party members which accompanied his rise to power. Indeed, he boasted that his indulgent parent had allowed him to execute some of the prisoners himself as "training" for a party activist.
His first public position was chairman of the Iraqi Olympic committee in 1987. He used the post to involve himself in a number of aspects of Iraqi public life, setting up a ministry of youth to promote himself and, ostensibly, the aspirations of a new generation of Iraqis.
In the autumn of 1988, however, his temper got the better of him when he murdered one of his father's closest aides, Kamil Jajo, in a fit of rage. Uday was sent to prison, where he languished for a month or so until his father pardoned him, purportedly because of the overwhelming number of pleas for clemency. He was sent into exile in Geneva, but was soon expelled by the Swiss authorities for possessing an illegal firearm.
He returned to Iraq in time for the invasion of Kuwait in 1990, where he and his associates were prominent in extensive and systematic looting. It was after Iraq's expulsion from Kuwait in 1991 that he became more visible as a public figure in Iraq.
His smuggling and racketeering operations increased, extending throughout the Iraqi economy into the media, food-processing, transport and - most lucratively of all - the covert export of oil. This led him into conflict with other members of the ruling family, most notably Wathban al-Tikriti (one of Saddam's half-brothers) and Hussein Kamil al-Majid (a son-in-law of Saddam).
Heading an organisation called the Saddamists Union, which provided perks for senior officials and spawned a militia of young thugs, called Firqat Fida'iyyin Saddam (Legion of Saddam's Fighters), Uday became an increasingly dangerous figure.
When he shot and wounded Wathban al-Tikriti at another public occasion in 1995, he seems to have precipitated his brother-in-law Hussein Kamil's flight into exile. Upon Kamil's ill-advised return to Iraq in 1996, Uday was one of the family members who organised his murder.
In December 1996 his violent past caught up with him. There was an attempt to assassinate him as he drove through Baghdad. He survived, but was severely wounded, and it took more than a year for him to appear in public again.
In May 2000 he ensured that he was elected to the national assembly, although his enthusiasm for the place fell dramatically when his father refused to allow him to be elected its speaker. Thereafter, he concentrated on self-enrichment, resentful of his younger brother Qusay's elevation to the role of heir.
Uday had a $15 million reward on his head as No 3 on the coalition's list of 55 most-wanted from the ousted regime - only Saddam and Qusay ranked higher.
Saddam's younger son, Qusay Saddam Hussein, who has died aged 37, was being groomed by his father as a successor. As war loomed in 2003, it was Qusay whom Saddam Hussein placed in command of the central military region, charged with defending the heartland of the regime in Baghdad and Tikrit.
Before that he had been entrusted with organising the personal protection of his father, as well as with overseeing Iraq's complex intelligence apparatus. He thus embodied the dynastic principle behind Saddam's rule of Iraq, as well as the practical principle of only trusting close family members with the key levers of power.
He was 13 when his father became president of Iraq in 1979. Less volatile than Uday and much less visible in the playgrounds of the elite in Baghdad, Qusay's systematic and ruthless intelligence had been recognised by his father who, it is said, saw in Qusay a reflection of his younger self.
It was for this reason that in 1988 he was appointed deputy director of al-Amn al-Khass (the Special Security Organisation), a powerful agency in Iraq, closest to the president and responsible for his personal security. By 1992 he had become its director.
Among his responsibilities was the supervision of the concealment operations committee (COC), the body charged by Saddam with concealing as much as possible of Iraq's weapons of mass destruction programme from the eyes of the UN weapons inspectors.
By 2002 he had become even more powerful in the Iraqi state. He was commander of the Special Republican Guard. Its units had been formed in 1991 to defend the regime and to deter the regular army, including the Republican Guard itself, from trying to threaten the president.
In 1996, following the abortive CIA/Iraqi National Accord coup plot of that year, Saddam appointed Qusay head of the special committee which brought all the branches of Iraqi intelligence together to investigate the conspiracy. In his mistrust of all those he interrogated and his ruthlessness in dealing with suspects, he showed himself well able to handle the ferocious task with which his father had entrusted him. His use of exemplary cruelty and his contempt for those he had in his power were strongly reminiscent of the methods and attitude of his father.
He was able to deploy these qualities further when Saddam allowed him, also from 1996, to chair the National Security Council, the supreme oversight body, bringing together all of Iraq's five security and intelligence organisations, as well as the staff of the president himself.
From this position, he was able to investigate all branches of the Iraqi state, to build up information on all the economic dealings of the Iraqi elite, including those of his brother and other members of the president's family, as well as to establish close links with key units in the Iraqi armed forces.
In May 2001 he was elected to the regional command of the Baath party; he was being transformed into the crown prince of Iraq.
The brothers met their end during a firefight in Mosul last Tuesday, after US forces, acting on a tip, stormed the villa where they were hiding. The brothers are survived by their mother and sisters. The fate of their father is not known. A teenage boy killed with the brothers may have been Qusay's son.
Uday Saddam Hussein: born June 18th, 1964; died July 22nd, 2003. Qusay Saddam Hussein: born 1966; died July 22nd, 2003.