Who exactly was the black-winged god of love? What secrets this masterwork reveals about the rebellious genius

A young lad screams as his skull is forcefully held, a massive digit digging into his cheek as his father's powerful palm grasps him by the neck. This scene from Abraham's Sacrifice visits the Uffizi Gallery, creating unease through the artist's harrowing portrayal of the suffering youth from the scriptural narrative. The painting seems as if Abraham, commanded by the Divine to kill his son, could snap his spinal column with a single twist. Yet the father's chosen approach involves the metallic steel knife he holds in his remaining hand, prepared to cut Isaac's neck. One certain aspect stands out – whomever posed as Isaac for this breathtaking work displayed extraordinary acting ability. There exists not only fear, shock and begging in his shadowed gaze but additionally profound sorrow that a protector could betray him so completely.

He adopted a well-known scriptural tale and made it so vibrant and visceral that its horrors seemed to happen right in view of the viewer

Viewing before the artwork, viewers identify this as a actual countenance, an precise record of a adolescent model, because the identical boy – identifiable by his tousled locks and almost black eyes – appears in several other paintings by the master. In each case, that richly emotional face commands the composition. In Youth With a Ram, he gazes mischievously from the shadows while holding a lamb. In Victorious Cupid, he grins with a toughness learned on Rome's alleys, his dark feathery appendages sinister, a naked child creating chaos in a affluent dwelling.

Victorious Cupid, presently exhibited at a British gallery, constitutes one of the most discomfiting masterpieces ever created. Viewers feel completely disoriented gazing at it. The god of love, whose darts fill people with frequently painful desire, is shown as a extremely real, vividly illuminated nude form, straddling overturned items that include musical instruments, a musical score, metal armor and an builder's T-square. This heap of possessions resembles, deliberately, the geometric and construction gear strewn across the ground in the German master's engraving Melancholy – save here, the melancholic mess is caused by this grinning Cupid and the mayhem he can unleash.

"Affection sees not with the vision, but with the mind, / And thus is winged Love depicted sightless," penned Shakespeare, just before this work was produced around the early 1600s. But the painter's Cupid is not unseeing. He gazes directly at the observer. That countenance – ironic and rosy-faced, staring with bold confidence as he poses naked – is the identical one that shrieks in fear in Abraham's Test.

When the Italian master painted his multiple portrayals of the identical distinctive-appearing youth in the Eternal City at the start of the 17th century, he was the highly acclaimed sacred painter in a metropolis ignited by Catholic renewal. Abraham's Offering demonstrates why he was commissioned to decorate churches: he could take a biblical story that had been depicted many occasions before and make it so new, so raw and physical that the horror appeared to be occurring immediately in front of the spectator.

Yet there was another side to Caravaggio, apparent as quickly as he came in Rome in the winter that ended the sixteenth century, as a painter in his initial 20s with no mentor or supporter in the urban center, only skill and boldness. Most of the paintings with which he captured the holy metropolis's eye were everything but devout. What may be the very first resides in the UK's art museum. A youth opens his red mouth in a scream of pain: while reaching out his filthy digits for a fruit, he has rather been bitten. Youth Bitten by a Reptile is sensuality amid squalor: observers can see Caravaggio's dismal chamber reflected in the murky liquid of the transparent vase.

The adolescent sports a pink blossom in his coiffure – a symbol of the erotic trade in Renaissance painting. Venetian painters such as Tiziano and Jacopo Palma portrayed courtesans holding flowers and, in a work destroyed in the second world war but documented through images, Caravaggio represented a famous female courtesan, holding a bouquet to her bosom. The message of all these floral indicators is obvious: sex for sale.

What are we to interpret of the artist's erotic depictions of youths – and of one adolescent 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 neither the queer hero that, for instance, Derek Jarman put on film in his twentieth-century film Caravaggio, nor so entirely pious that, as some art scholars unbelievably claim, his Youth Holding Fruit is in fact a likeness of Christ.

His early works indeed offer explicit sexual suggestions, or including propositions. It's as if the painter, then a destitute young artist, identified with Rome's prostitutes, offering himself to live. In the Uffizi, with this thought in consideration, viewers might look to another initial work, the sixteenth-century masterpiece the god of wine, in which the god of alcohol gazes coolly at the spectator as he begins to undo the dark sash of his robe.

A few annums after the wine deity, what could have driven Caravaggio to paint Amor Vincit Omnia for the art collector the nobleman, when he was finally becoming nearly established with prestigious church projects? This unholy non-Christian deity resurrects the sexual challenges of his initial paintings but in a more intense, uneasy manner. Half a century later, its secret seemed obvious: it was a portrait of Caravaggio's companion. A British traveller viewed the painting in about 1649 and was told its subject has "the body & face of [Caravaggio's|his] owne youth or servant that laid with him". The name of this boy was Cecco.

The painter had been dead for about 40 annums when this story was documented.