Who exactly was Caravaggio's dark-feathered deity of desire? What insights this masterwork reveals about the rebellious genius

A youthful lad screams while his head is firmly gripped, a massive thumb pressing into his cheek as his father's powerful hand grasps him by the neck. This scene from Abraham's Sacrifice visits the Florentine museum, evoking distress through the artist's harrowing portrayal of the tormented child from the biblical account. The painting appears as if the patriarch, instructed by the Divine to sacrifice his offspring, could break his neck with a single twist. However the father's chosen method involves the silvery steel blade he holds in his other palm, ready to cut the boy's throat. A definite element remains – whomever modeled as Isaac for this breathtaking piece displayed extraordinary acting ability. Within exists not only fear, surprise and begging in his shadowed eyes but also profound grief that a protector could betray him so utterly.

He adopted a well-known biblical story and transformed it so fresh and raw that its horrors seemed to unfold right in view of you

Viewing before the artwork, observers recognize this as a actual face, an accurate record of a young model, because the identical boy – recognizable by his disheveled locks and nearly black pupils – features in two additional paintings by the master. In each case, that highly expressive face commands the scene. In Youth With a Ram, he gazes mischievously from the darkness while embracing a lamb. In Amor Vincit Omnia, he smirks with a hardness acquired on Rome's streets, his black plumed appendages sinister, a naked child creating riot in a well-to-do dwelling.

Amor Vincit Omnia, currently displayed at a London gallery, represents one of the most discomfiting masterpieces ever painted. Viewers feel totally unsettled gazing at it. Cupid, whose darts fill people with frequently agonizing longing, is portrayed as a extremely tangible, brightly illuminated nude form, straddling toppled-over objects that comprise musical instruments, a music score, plate armor and an architect's T-square. This heap of possessions resembles, deliberately, the geometric and architectural equipment strewn across the floor in the German master's print Melancholy – save here, the gloomy mess is caused by this smirking deity and the turmoil he can release.

"Love looks not with the eyes, 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 Cupid is not blind. He stares directly at the observer. That face – ironic and rosy-cheeked, staring with bold confidence as he struts naked – is the identical one that screams in fear in Abraham's Test.

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

Yet there existed a different side to the artist, evident as soon as he arrived in Rome in the cold season that concluded the sixteenth century, as a artist in his initial 20s with no teacher or patron in the urban center, only talent and boldness. Most of the paintings with which he captured the holy metropolis's eye were everything but devout. That may be the very earliest resides in the UK's art museum. A young man opens his red mouth in a scream of pain: while stretching out his dirty digits for a cherry, he has rather been bitten. Youth Bitten by a Reptile is sensuality amid squalor: observers can see the painter's dismal chamber mirrored in the cloudy waters of the glass container.

The adolescent wears a rose-colored blossom in his coiffure – a symbol of the erotic commerce in early modern painting. Northern Italian painters such as Titian and Palma Vecchio portrayed prostitutes holding blooms and, in a work destroyed in the WWII but documented through photographs, the master represented a famous woman courtesan, clutching a bouquet to her chest. The meaning of all these botanical signifiers is obvious: intimacy for sale.

How are we to interpret of the artist's erotic portrayals of youths – and of one boy in specific? It is a question that has split his commentators ever since he achieved mega-fame in the twentieth century. The complicated historical truth is that the painter was not the queer hero that, for example, Derek Jarman presented on film in his 1986 film Caravaggio, nor so completely pious that, as some art scholars unbelievably claim, his Boy With a Basket of Fruit is actually a portrait of Christ.

His initial paintings indeed offer overt sexual implications, or including offers. It's as if Caravaggio, then a penniless young creator, identified with Rome's prostitutes, offering himself to survive. In the Florentine gallery, with this idea in consideration, viewers might turn to another initial work, the sixteenth-century masterpiece Bacchus, in which the deity of wine gazes coolly at the spectator as he starts to untie the black ribbon of his garment.

A several years after the wine deity, what could have motivated Caravaggio to paint Amor Vincit Omnia for the artistic collector the nobleman, when he was at last becoming almost established with important ecclesiastical commissions? This profane pagan deity revives the sexual provocations of his initial paintings but in a more intense, uneasy manner. Fifty years afterwards, its secret seemed obvious: it was a portrait of the painter's companion. A English visitor saw the painting in about the mid-seventeenth century and was informed its subject has "the physique and countenance of [Caravaggio's|his] own youth or servant that laid with him". The identity of this adolescent was Francesco.

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