Theirs was a relationship borne out of the murky world where Russia's state security services mingled with the criminal underworld.
While Yevgeny Prigozhin's Wagner military company grew into one of the most influential structures in Russia, Vladimir Putin became increasingly dependent on its battlefield successes in Ukraine.
But it was in the seedy scene of early 1990s St Petersburg that their paths first met, during the politically fraught years after the collapse of the Soviet Union.
Both men originate from Russia's second city and cultural capital.
Home to the Hermitage art museum and Imperial Winter Palace, it is also considered the crime capital of Russia and a base for powerful gangs.
The exact circumstances of their first encounter are unknown, but Prigozhin was fresh out of jail and Mr Putin had recently returned from a mission in East Germany as an officer with the Soviet security service, the KGB, and was looking for a way into politics.
Convicted for the first time at 17, Prigozhin was no stranger to crime. After a suspended sentence for theft in the late 1970s, he was given a lengthy jail term for robbery in 1981.
He and two others had grabbed a woman by the neck in the street and tried to strangle her, before running off with her winter boots and earrings.
When he left prison in 1990, Russia was a very different place. Instead of the old Soviet chief, Leonid Brezhnev, reformist leader Mikhail Gorbachev was in power, the Berlin Wall had fallen and perestroika (restructuring) was well under way.
From hot dogs to foie gras
Prigozhin started out as a St Petersburg hot-dog salesman, but by the mid-1990s he had opened a restaurant. The Old Custom House is most likely the place the two men first met.
The menu of foie gras and oysters attracted local crime bosses as well as the city's powerful mayor, Anatoly Sobchak. Vladimir Putin, then aged 40, went there too as Sobchak's deputy.
Prigozhin's single restaurant became a chain and his clientele included politicians from far beyond St Petersburg.
By the turn of the century, when Mr Putin became president, the two men had become close associates and Prigozhin's nickname, Putin's chef, dates back to this time.
A photo shows Prigozhin serving dinner to him and President George W Bush.
For a man such as Russia's new leader, it was imperative to have a personal chef to ensure his food was safe to consume.
Ever the suspicious KGB mind, he had also served as the head of its successor, the FSB.
It was also convenient to have a man whose innermost secrets he would have known and whom he could influence.
With Vladimir Putin in the Kremlin, Russia's security services slowly began to take back control. Prigozhin took on a variety of Kremlin tasks, particularly those beyond the security services' reach.
Their association was now at arm's length, so the man in the Kremlin could plausibly deny involvement.
Prigozhin set up a media empire focused on spreading disinformation within Russia and abroad. The stories it invented were often so fantastical that no state propaganda apparatus would dare to spread them.
As social media began to gain influence, he set up a "troll factory" whose main effect was to leave Russians with the feeling there was no such thing as truth and no point looking for it.
It took another decade before he admitted to being the brains behind the "Internet Research Agency".
After the Ukrainian Maidan Revolution in 2013-14 and Russia's annexation of Crimea, the first reports of the Wagner private military company surfaced. Wagner supported pro-Russian separatists in Crimea and in the east of Ukraine.
Mercenary organisations are banned by Russian law, even though Prigozhin and his mercenaries had become increasingly important for stamping President Putin's authority.
So until as late as spring 2022, the Kremlin maintained that it had no connection to him.
Wagner also played a prominent role in Syria - and this is when its ruthless commander, Dmitry Utkin, first came into view as Prigozhin's close associate. The mercenary group has for years been active in a number of African countries, from Libya and Mali to Central African Republic.
But officially, Prigozhin had no special relationship with the president.
Mr Putin or his press secretary Dmitry Peskov would say merely that they were aware of the existence of a Russian "private businessman" who was involved in those activities. But it was clear such operations couldn't be conducted without Kremlin consent.
President Putin only admitted in June that Wagner had received enormous state funding for years and that its mercenaries had fought valiantly in battle. And yet because private military companies were illegal, he said that as a group, they did not exist.
It was not until the summer of 2022 that reports emerged of Wagner fighting in Ukraine.
Within weeks, Prigozhin was touring Russian prisons, recruiting inmates for the war effort.
The Kremlin spokesman spoke of him as a man "whose heart aches for what's happening" and one who was "making a big contribution".
Prigozhin opened a Wagner Centre in St Petersburg in November and his criticisms of the Russian army and the defence ministry became more vocal.
As Russian forces were forced into a series of retreats in Ukraine, his criticism reached a peak.
He complained that the army command was refusing to recognise the mercenaries' contribution to the war effort.
Later, he openly accused Defence Minister Sergei Shoigu and the Chief of the General Staff, Valery Gerasimov, of "starving" Wagner of ammunition while the group was losing thousands of men in the fight for Bakhmut in the east of Ukraine.
At one point, Prigozhin even aimed his criticism at the president, referring to him with the Russian word for grandad.
"How can we win a war when dedushka is a moron?"
He did not name Putin, but Russians were left in no doubt he was directly implicating him.
The Kremlin steered clear of commenting on the escalating feud, but it was a row that would shake Russia's leadership to its core and ultimately bring down Prigozhin.
He refused a defence ministry demand to bring all mercenary groups under its control. As the situation reached boiling point, he dared to question the very goals of the war.
On 23 June, he announced a "march for justice" on the road to Moscow.
Sources have told the BBC that his mutiny was a sign of Prigozhin's desperation and an attempt to attract President Putin's attention to his conflict with the Russian military.
"He was worried about losing his autonomy," one source who knew Prigozhin explained.
Wagner mercenaries shot down two military helicopters and a plane and killed up to 15 Russian soldiers.
Without naming him personally, President Putin described Prigozhin as a traitor who "drove a knife in the back of the country".
This botched revolt was to be the final rupture between them.
Days after the rebellion had ended in failure, Vladimir Putin met his former ally at the Kremlin for three hours, along with more than 30 Wagner commanders.
Vladimir Putin had no more need of him, but there were still questions over the fate of his men.
Prigozhin clearly believed his future lay in Africa and his final online video was purportedly filmed in an African field where he claimed: "Here we are, putting God's fear into Isis, al-Qaeda and other bandits."
But his story appears to have come to an end soon afterwards, following a trajectory similar to other examples in Russian history. A man handed the task of executing the Kremlin's cruellest policies was himself brutally punished and ultimately destroyed.
Or in Vladimir Putin's own assessment: "He was a man with a difficult fate and he made serious mistakes in life."