What exactly was the black-winged god of love? The secrets this masterpiece uncovers about the rogue artist

The young boy cries out while his head is firmly held, a massive digit digging into his face as his father's mighty palm grasps him by the throat. This moment from The Sacrifice of Isaac appears in the Florentine museum, creating unease through the artist's chilling portrayal of the tormented youth from the scriptural account. The painting appears as if the patriarch, commanded by the Divine to kill his son, could snap his neck with a solitary turn. Yet Abraham's chosen approach involves the metallic steel knife he holds in his remaining hand, prepared to slit the boy's neck. A definite element remains – whoever posed as Isaac for this astonishing piece demonstrated remarkable expressive ability. Within exists not just fear, surprise and begging in his darkened gaze but additionally deep sorrow that a guardian could abandon him so completely.

He adopted a familiar biblical tale and transformed it so vibrant and raw that its horrors seemed to happen right in view of the viewer

Standing in front of the painting, viewers recognize this as a actual face, an accurate record of a young model, because the same boy – recognizable by his disheveled locks and almost dark pupils – appears in two additional works by the master. In every instance, that richly emotional face commands the composition. In Youth With a Ram, he peers mischievously from the darkness while embracing a lamb. In Victorious Cupid, he grins with a hardness learned on the city's alleys, his black feathery appendages demonic, a unclothed child running riot in a affluent residence.

Amor Vincit Omnia, presently exhibited at a British gallery, constitutes one of the most embarrassing masterpieces ever painted. Viewers feel totally unsettled looking at it. Cupid, whose darts fill people with frequently painful longing, is shown as a very tangible, brightly illuminated unclothed figure, straddling overturned items that comprise stringed devices, a music score, plate armour and an builder's T-square. This heap of items resembles, deliberately, the mathematical and construction gear strewn across the floor in Albrecht Dürer's print Melancholy – except here, the melancholic disorder is created by this grinning deity and the mayhem he can unleash.

"Love looks not with the vision, but with the soul, / And thus is winged Cupid painted sightless," penned the Bard, shortly prior to this painting was created around the early 1600s. But Caravaggio's Cupid is not blind. He stares straight at the observer. That countenance – sardonic and rosy-faced, staring with brazen confidence as he poses naked – is the identical one that screams in fear in The Sacrifice of Isaac.

When the Italian master painted his three images of the identical distinctive-looking youth in Rome at the start of the 17th century, he was the highly acclaimed religious artist in a metropolis enflamed by religious renewal. The Sacrifice of Isaac reveals why he was sought to adorn sanctuaries: he could adopt a biblical narrative that had been portrayed numerous occasions before and render it so fresh, so raw and physical that the horror seemed to be happening immediately before the spectator.

However there was another side to the artist, evident as quickly as he arrived in Rome in the cold season that ended 1592, as a painter in his initial twenties with no teacher or patron in the city, just talent and audacity. Most of the paintings with which he captured the sacred city's attention were anything but devout. What could be the absolute earliest resides in London's National Gallery. A youth opens his crimson lips in a scream of pain: while reaching out his filthy fingers for a fruit, he has rather been attacked. Boy Bitten By a Lizard is eroticism amid squalor: viewers can see Caravaggio's dismal room reflected in the murky waters of the glass vase.

The adolescent wears a rose-colored flower in his coiffure – a symbol of the erotic commerce in early modern art. Northern Italian artists such as Titian and Palma Vecchio depicted prostitutes holding blooms and, in a painting lost in the WWII but known through images, Caravaggio represented a renowned female courtesan, clutching a posy to her bosom. The message of all these botanical signifiers is clear: sex for purchase.

How are we to interpret of Caravaggio's erotic depictions of youths – and of a particular boy in particular? It is a question that has split his interpreters since he gained mega-fame in the twentieth century. The complex past truth is that the artist was not the queer icon that, for example, the filmmaker put on screen in his 1986 movie Caravaggio, nor so entirely pious that, as certain art historians unbelievably assert, his Boy With a Basket of Fruit is in fact a likeness of Jesus.

His early works do make overt erotic implications, or even propositions. It's as if Caravaggio, then a penniless youthful artist, identified with the city's prostitutes, offering himself to survive. In the Florentine gallery, with this idea in mind, observers might turn to another early work, the sixteenth-century masterwork Bacchus, in which the god of wine gazes coolly at you as he begins to untie the black sash of his garment.

A few years after the wine deity, what could have driven the artist to create Amor Vincit Omnia for the art collector Vincenzo Giustiniani, when he was at last growing almost established with important church projects? This profane pagan deity revives the erotic provocations of his early paintings but in a increasingly intense, uneasy way. Half a century afterwards, its hidden meaning seemed obvious: it was a representation of the painter's companion. A English visitor saw Victorious Cupid in about the mid-seventeenth century and was informed its subject has "the body & face of [Caravaggio's|his] owne boy or assistant that slept with him". The name of this adolescent was Francesco.

The artist had been deceased for about 40 annums when this account was documented.