Whether it was tucking children into bed or sending his chauffeur to pick up rain-soaked people at a bus stop, Stalin: The Court of the Red Tsar may show a side to the former Russian premier never seen before.
This is because Simon Montefiore wrote his biography after spending three years in Russian archives that were never opened to the West until the fall of the Soviet Union.
So now we know that the dictator loved gardening, John Wayne movies and classic novels like The Last of the Mohicans.
But the historian does not deny that Stalin was ultimately responsible for ordering the deaths of an estimated 20 million people too, from close friends to complete strangers.
The book, first published in Britain, came out in the United States in April.
Montefiore, whose earlier book on Russia dealt with Catherine the Great's lover Prince Potemkin, believes the secret of Stalin's success was his charm.
Filling in the details with all too human touches of a man growing old and cold, the study reveals a man able to kill more and more as the years went on until his death in 1953 cut short what would have been a massive purge of Jews in the Soviet Union.
But Montefiore said, "Charm is how Stalin built his dictatorship. If he set his mind to charm you, he was irresistible."
"He had been killing people since 1918 when he discovered the axiom, 'One man, one problem. No man, no problem'"
biographer and historian
Stalin, said Montefiore, was accessible to his officials, cared for their wives and children, showered all with attention, even answered the phone himself.
"Stalin became absolute dictator much later than anyone realised. Stalin only became dictator with life and death powers in 1937; none of his inner circle were terrified of him until then.
"He set off the Great Terror because he felt he was special and not being given the deference he deserved, but he had been killing people since 1918 when he discovered the axiom, 'One man, one problem. No man, no problem'."
Mannerisms and mistakes
His toadies "studied Stalin like zoologists to read his moods, win his favour and survive," Montefiore said.
They could tell his mood by the way he held his pipe: "if [it] was unlit, it was a bad omen. If Stalin put it down, an explosion was imminent ... if he stroked his moustache with the mouthpiece ... he was pleased."
The historian believes Stalin's biggest mistake was not to realise that his Nazi-Soviet pact partner Hitler was about to invade Russia.
Montefiore said Stalin admitted he was wrong saying, "when you're trying to make a decision, never put yourself into the mind of the other person because if you do, you can make a terrible mistake."
It made no sense to him to attack Russia when Hitler did. He expected him to wait until after he got rid of the British, that was what Stalin would have done.