What exactly was Caravaggio's dark-feathered god of love? What secrets that masterpiece uncovers about the rebellious artist

A young lad cries out while his skull is forcefully held, a massive digit digging into his cheek as his parent's mighty palm holds him by the throat. That moment from The Sacrifice of Isaac visits the Florentine museum, evoking distress through Caravaggio's chilling portrayal of the tormented child from the scriptural account. The painting seems as if Abraham, commanded by God to kill his offspring, could break his neck with a solitary turn. However Abraham's chosen method involves the silvery steel blade he holds in his other hand, ready to slit Isaac's throat. A definite element remains – whomever modeled as Isaac for this astonishing piece demonstrated extraordinary expressive skill. There exists not only fear, shock and pleading in his shadowed eyes but additionally deep grief that a guardian could abandon him so completely.

He took a familiar biblical story and transformed it so vibrant and raw that its terrors appeared to happen directly in front of the viewer

Viewing in front of the artwork, observers identify this as a real countenance, an accurate depiction of a adolescent model, because the same boy – identifiable by his disheveled hair and nearly black pupils – features in several other paintings by Caravaggio. In each instance, that richly expressive visage dominates the scene. In John the Baptist, he gazes playfully from the darkness while embracing a lamb. In Amor Vincit Omnia, he smirks with a toughness acquired on Rome's alleys, his dark feathery appendages sinister, a unclothed adolescent running chaos in a affluent residence.

Victorious Cupid, currently displayed at a British gallery, constitutes one of the most embarrassing masterpieces ever created. Viewers feel completely unsettled gazing at it. The god of love, whose arrows inspire people with often painful desire, is shown as a very real, vividly illuminated unclothed form, straddling toppled-over objects that include stringed instruments, a musical score, plate armor and an builder's T-square. This heap of possessions echoes, deliberately, the mathematical and architectural equipment strewn across the ground in Albrecht Dürer's engraving Melencolia I – except in this case, the gloomy disorder is created by this smirking Cupid and the mayhem he can release.

"Affection sees not with the vision, but with the mind, / And thus is feathered Cupid depicted sightless," wrote the Bard, shortly before this painting was produced around 1601. But the painter's god is not blind. He stares straight at you. That face – sardonic and rosy-faced, looking with brazen assurance as he struts naked – is the identical one that screams in terror in The Sacrifice of Isaac.

When the Italian master created his three images of the same distinctive-appearing youth in Rome at the dawn of the 17th century, he was the most celebrated religious painter in a metropolis ignited by Catholic renewal. Abraham's Offering demonstrates why he was commissioned to adorn sanctuaries: he could adopt a scriptural story that had been portrayed many times before and make it so new, so unfiltered and physical that the horror appeared to be occurring immediately before you.

Yet there existed a different aspect to Caravaggio, evident as quickly as he came in Rome in the cold season that ended the sixteenth century, as a painter in his early twenties with no mentor or patron in the city, only skill and boldness. The majority of the paintings with which he caught the holy metropolis's attention were anything but holy. That could be the very first resides in London's art museum. A youth parts his crimson lips in a scream of pain: while stretching out his dirty fingers for a cherry, he has instead been attacked. Youth Bitten by a Reptile is eroticism amid squalor: viewers can see the painter's dismal chamber reflected in the murky waters of the glass vase.

The boy sports a pink flower in his hair – a symbol of the erotic trade in Renaissance painting. Northern Italian artists such as Titian and Jacopo Palma depicted prostitutes grasping blooms and, in a painting destroyed in the second world war but known through photographs, Caravaggio represented a renowned female prostitute, holding a posy to her bosom. The message of all these botanical indicators is obvious: intimacy for sale.

What are we to make of Caravaggio's erotic portrayals of youths – and of one boy in specific? It is a inquiry that has divided his interpreters since he achieved widespread recognition in the 1980s. The complicated historical reality is that the painter was not the queer icon that, for instance, Derek Jarman put on screen in his 1986 movie Caravaggio, nor so entirely pious that, as certain art scholars unbelievably assert, his Boy With a Basket of Fruit is actually a portrait of Jesus.

His early works do offer explicit sexual implications, or even propositions. It's as if Caravaggio, then a penniless youthful creator, identified with the city's sex workers, offering himself to survive. In the Florentine gallery, with this thought in mind, viewers might turn to another initial work, the 1596 masterwork Bacchus, in which the deity of wine gazes calmly at you as he starts to untie the dark ribbon of his robe.

A few annums following Bacchus, what could have driven the artist to paint Amor Vincit Omnia for the artistic collector the nobleman, when he was finally growing almost established with prestigious church projects? This profane non-Christian deity revives the sexual challenges of his initial paintings but in a more powerful, unsettling manner. Half a century afterwards, its secret seemed clear: it was a representation of Caravaggio's companion. A British visitor viewed Victorious Cupid in about the mid-seventeenth century and was told its figure has "the physique and countenance of [Caravaggio's|his] own boy or servant that laid with him". The name of this adolescent was Cecco.

The artist had been deceased for about 40 years when this account was recorded.