Who exactly was the black-winged deity of desire? What insights this masterpiece uncovers about the rebellious artist

A youthful boy cries out while his head is forcefully gripped, a massive thumb pressing into his cheek as his parent's mighty hand grasps him by the neck. This scene from Abraham's Sacrifice visits the Florentine museum, evoking unease through the artist's chilling rendition of the tormented youth from the biblical narrative. The painting seems as if the patriarch, commanded by the Divine to sacrifice his son, could break his neck with a solitary turn. Yet Abraham's chosen approach involves the silvery steel blade he grips in his remaining hand, ready to cut Isaac's neck. A certain aspect stands out – whoever modeled as the sacrifice for this breathtaking work demonstrated remarkable expressive ability. Within exists not only dread, surprise and pleading in his darkened eyes but also profound sorrow that a protector could abandon him so utterly.

The artist adopted a well-known biblical tale and transformed it so vibrant and raw that its terrors appeared to happen directly in view of the viewer

Standing before the artwork, observers recognize this as a actual countenance, an accurate depiction of a adolescent subject, because the identical boy – identifiable by his tousled locks and almost black pupils – appears in two additional works by the master. In every case, that richly emotional visage commands the composition. In John the Baptist, he peers mischievously from the darkness while embracing a lamb. In Victorious Cupid, he smirks with a toughness learned on the city's streets, his black plumed wings demonic, a naked child creating riot in a well-to-do residence.

Amor Vincit Omnia, presently displayed at a London gallery, represents one of the most embarrassing masterpieces ever created. Viewers feel totally disoriented gazing at it. The god of love, whose arrows inspire people with often painful longing, is shown as a very real, vividly illuminated nude form, straddling overturned objects that include musical instruments, a music score, metal armor and an architect's ruler. This heap of items echoes, intentionally, the mathematical and architectural equipment scattered across the floor in Albrecht Dürer's print Melancholy – except here, the gloomy disorder is created by this smirking deity and the turmoil he can unleash.

"Love looks not with the eyes, but with the soul, / And therefore is feathered Love depicted sightless," penned the Bard, shortly before this painting was created around 1601. But the painter's god is not blind. He stares directly at the observer. That countenance – sardonic and ruddy-faced, looking with bold assurance as he poses unclothed – is the same one that shrieks in terror in The Sacrifice of Isaac.

When the Italian master painted his multiple images of the same unusual-looking kid in Rome at the start of the 17th century, he was the most celebrated sacred painter in a metropolis enflamed by Catholic revival. Abraham's Offering demonstrates why he was sought to adorn sanctuaries: he could adopt a scriptural story that had been depicted numerous occasions before and make it so fresh, so raw and physical that the terror appeared to be occurring immediately in front of the spectator.

Yet there was a different aspect to Caravaggio, apparent as quickly as he came in the capital in the cold season that ended the sixteenth century, as a artist in his initial 20s with no mentor or supporter in the urban center, just talent and audacity. Most of the paintings with which he caught the sacred city's attention were everything but devout. What could be the very first hangs in London's art museum. A young man parts his red mouth in a scream of agony: while reaching out his dirty fingers for a fruit, he has rather been bitten. Boy Bitten By a Lizard is sensuality amid squalor: observers can see Caravaggio's gloomy room reflected in the murky waters of the glass container.

The boy wears a rose-colored blossom in his hair – a emblem of the sex trade in Renaissance art. Venetian artists such as Tiziano and Palma Vecchio portrayed prostitutes grasping blooms and, in a work destroyed in the second world war but documented through images, the master portrayed a famous female prostitute, clutching a posy to her bosom. The message of all these floral indicators is obvious: sex for purchase.

How are we to make of the artist's erotic depictions of boys – and of one boy in particular? It is a question that has split his commentators since he achieved mega-fame in the twentieth century. The complex historical reality is that the painter was neither the homosexual icon that, for instance, Derek Jarman presented on film in his 1986 film Caravaggio, nor so completely pious that, as some artistic historians unbelievably claim, his Boy With a Basket of Fruit is actually a likeness of Christ.

His initial paintings do make overt sexual implications, or including offers. It's as if Caravaggio, then a penniless young creator, aligned with Rome's sex workers, offering himself to survive. In the Uffizi, with this idea in consideration, observers might turn to an additional initial creation, the sixteenth-century masterpiece the god of wine, in which the deity of alcohol stares coolly at the spectator as he starts to undo the dark sash of his robe.

A several years after the wine deity, what could have motivated the artist to create Victorious Cupid for the art collector Vincenzo Giustiniani, when he was finally becoming almost established with important ecclesiastical commissions? This unholy non-Christian god revives the erotic provocations of his early works but in a more powerful, unsettling way. Fifty years afterwards, its secret seemed obvious: it was a portrait of the painter's lover. A British visitor saw Victorious Cupid in about 1649 and was told its subject has "the body & face of [Caravaggio's|his] own boy or assistant that slept with him". The name of this boy was Francesco.

The painter had been dead for about forty annums when this account was documented.