Who exactly was Caravaggio's dark-feathered god of desire? What secrets this masterwork reveals about the rogue artist

The youthful boy cries out while his head is forcefully gripped, a massive thumb pressing into his cheek as his parent's powerful palm grasps him by the neck. This moment from Abraham's Sacrifice visits the Florentine museum, evoking unease through Caravaggio's chilling portrayal of the tormented child from the biblical account. The painting appears as if Abraham, commanded by God to kill his offspring, could break his spinal column with a single turn. Yet Abraham's chosen method involves the silvery grey blade he holds in his remaining hand, prepared to cut the boy's neck. A definite element stands out – whoever modeled as Isaac for this astonishing work demonstrated remarkable acting skill. There exists not just fear, shock and begging in his darkened gaze but additionally profound sorrow that a protector could abandon him so completely.

He took a well-known scriptural tale and made it so fresh and raw that its horrors appeared to unfold right in front of you

Standing before the artwork, observers recognize this as a real countenance, an accurate record of a adolescent model, because the same boy – identifiable by his disheveled locks and nearly dark eyes – appears in several additional works by Caravaggio. In every instance, that richly expressive visage commands the scene. In John the Baptist, he gazes playfully from the shadows while holding a lamb. In Victorious Cupid, he smirks with a hardness acquired on the city's alleys, his dark plumed appendages sinister, a unclothed adolescent creating chaos in a affluent dwelling.

Amor Vincit Omnia, presently exhibited at a British museum, represents one of the most embarrassing masterpieces ever created. Observers feel completely disoriented gazing at it. Cupid, whose arrows fill people with frequently agonizing longing, is shown as a extremely tangible, brightly lit unclothed figure, standing over overturned items that comprise stringed devices, a musical manuscript, metal armor and an architect's T-square. This heap of items resembles, deliberately, the mathematical and architectural gear strewn across the ground in the German master's engraving Melancholy – except here, the gloomy disorder is created by this smirking Cupid and the turmoil he can unleash.

"Love sees not with the eyes, but with the soul, / And therefore is feathered Love painted sightless," penned Shakespeare, just prior to this work was created around the early 1600s. But Caravaggio's god is not unseeing. He stares directly at you. That countenance – ironic and ruddy-faced, looking with bold confidence as he struts naked – is the same one that shrieks in fear in Abraham's Test.

When the Italian master painted his multiple portrayals of the same distinctive-looking youth in Rome at the start of the seventeenth century, he was the most acclaimed religious painter in a city enflamed by religious revival. The Sacrifice of Isaac demonstrates why he was sought to adorn churches: he could adopt a biblical narrative that had been depicted many times before and make it so new, so unfiltered and visceral that the terror seemed to be occurring immediately in front of you.

Yet there existed another aspect to Caravaggio, evident as soon as he arrived in the capital in the cold season that ended 1592, as a painter in his initial 20s with no teacher or patron in the city, just talent and boldness. The majority of the paintings with which he caught the sacred metropolis's attention were anything but holy. What could be the very earliest hangs in the UK's art museum. A youth parts his red lips in a scream of agony: while reaching out his dirty fingers for a cherry, he has rather been attacked. Youth Bitten by a Reptile is sensuality amid squalor: viewers can discern the painter's dismal room mirrored in the cloudy liquid of the glass container.

The boy wears a pink blossom in his coiffure – a symbol of the sex commerce in early modern painting. Northern Italian painters such as Titian and Palma Vecchio depicted prostitutes holding blooms and, in a work destroyed in the WWII but known through photographs, Caravaggio portrayed a famous female prostitute, holding a bouquet to her bosom. The meaning of all these floral indicators is obvious: intimacy for purchase.

How are we to interpret of Caravaggio's erotic portrayals of youths – and of a particular adolescent in specific? It is a question that has split his interpreters ever since he gained mega-fame in the twentieth century. The complex historical truth is that the painter was not the queer hero that, for instance, Derek Jarman presented on film in his 1986 movie about the artist, nor so completely devout that, as some artistic scholars unbelievably assert, his Boy With a Basket of Fruit is in fact a likeness of Jesus.

His early works indeed make explicit erotic suggestions, or even offers. It's as if the painter, then a penniless young artist, identified with the city's sex workers, offering himself to live. In the Uffizi, with this idea in mind, observers might turn to an additional early creation, the sixteenth-century masterwork the god of wine, in which the deity of alcohol stares calmly at the spectator as he begins to undo the dark ribbon of his robe.

A several annums following the wine deity, what could have motivated the artist to create Victorious Cupid for the art collector the nobleman, when he was finally growing nearly established with prestigious church commissions? This profane non-Christian deity resurrects the erotic challenges of his early works but in a more intense, unsettling manner. Half a century afterwards, its secret seemed clear: it was a representation of Caravaggio's companion. A British visitor saw the painting in about 1649 and was told its figure has "the body & face of [Caravaggio's|his] owne youth or servant that laid with him". The name of this adolescent was Cecco.

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

Heather Reid
Heather Reid

Award-winning journalist with a focus on Central European affairs and investigative reporting.