What exactly was Caravaggio's black-winged deity of desire? What insights that masterpiece uncovers about the rebellious genius

A young boy screams as his head is forcefully held, a large thumb digging into his face as his father's mighty palm holds him by the throat. That moment from The Sacrifice of Isaac appears in the Florentine museum, evoking distress through the artist's chilling rendition of the tormented youth from the scriptural narrative. It seems as if the patriarch, instructed by the Divine to sacrifice his offspring, could snap his neck with a single twist. However the father's preferred method involves the metallic grey knife he holds in his other hand, ready to slit Isaac's throat. A definite aspect remains – whoever modeled as the sacrifice for this breathtaking work displayed remarkable acting skill. There exists not just fear, shock and begging in his darkened eyes but additionally profound sorrow that a protector could abandon him so completely.

He adopted a familiar scriptural tale and made it so fresh and raw that its horrors seemed to unfold directly in view of the viewer

Standing before the painting, viewers identify this as a actual face, an accurate record of a young subject, because the identical boy – identifiable by his disheveled locks and almost black eyes – features in several additional works by Caravaggio. In every instance, that highly expressive visage dominates the composition. In Youth With a Ram, he peers playfully from the darkness while holding a ram. In Amor Vincit Omnia, he smirks with a toughness learned on the city's alleys, his black feathery appendages sinister, a unclothed child running riot in a affluent residence.

Victorious Cupid, currently exhibited at a London museum, represents one of the most discomfiting artworks ever painted. Viewers feel completely disoriented gazing at it. Cupid, whose arrows fill people with frequently painful longing, is shown as a very real, vividly lit unclothed figure, straddling toppled-over items that include musical instruments, a musical manuscript, metal armor and an builder's ruler. This heap of items resembles, intentionally, the mathematical and construction equipment scattered across the ground in Albrecht Dürer's print Melancholy – except in this case, the gloomy disorder is created by this smirking deity and the mayhem he can unleash.

"Affection sees not with the vision, but with the soul, / And thus is winged Love painted sightless," wrote Shakespeare, just before this work was produced around the early 1600s. But Caravaggio's god is not blind. He stares directly at the observer. That countenance – sardonic and rosy-cheeked, looking with brazen confidence as he struts naked – is the identical one that screams in fear in Abraham's Test.

As the Italian master painted his multiple portrayals of the identical unusual-looking youth in the Eternal City at the dawn of the 17th century, he was the most celebrated sacred painter in a city enflamed by Catholic renewal. The Sacrifice of Isaac demonstrates why he was sought to decorate churches: he could take a scriptural story that had been depicted numerous occasions previously and render it so new, so unfiltered and visceral that the terror seemed to be occurring immediately in front of the spectator.

Yet there was a different side to Caravaggio, evident as quickly as he came in the capital in the winter that ended 1592, as a artist in his initial 20s with no mentor or patron in the city, just skill and boldness. Most of the works with which he caught the holy city's eye were everything but holy. That may be the very first hangs in London's National Gallery. A young man opens his crimson mouth in a scream of pain: while reaching out his dirty fingers for a cherry, he has rather been bitten. Boy Bitten By a Lizard is eroticism amid squalor: viewers can discern Caravaggio's gloomy room mirrored in the murky waters of the transparent container.

The boy sports a rose-colored flower in his coiffure – a symbol of the erotic commerce in early modern art. Northern Italian painters such as Titian and Palma Vecchio depicted prostitutes holding flowers and, in a painting lost in the WWII but known through images, the master represented a renowned female prostitute, clutching a posy to her chest. The meaning of all these floral indicators is obvious: intimacy for sale.

What are we to make of Caravaggio's sensual depictions of youths – and of a particular adolescent in particular? It is a inquiry that has divided his interpreters since he achieved widespread recognition in the 1980s. The complicated historical reality is that the artist was not the queer hero that, for example, Derek Jarman put on screen in his 1986 film Caravaggio, nor so completely devout that, as certain artistic historians unbelievably claim, his Youth Holding Fruit is actually a portrait of Jesus.

His initial works indeed make overt sexual implications, or including propositions. It's as if Caravaggio, then a penniless young artist, aligned with the city's sex workers, offering himself to survive. In the Florentine gallery, with this thought in mind, viewers might turn to an additional early work, the sixteenth-century masterwork Bacchus, in which the god of alcohol gazes coolly at the spectator as he begins to untie the black sash of his robe.

A several annums after Bacchus, what could have driven the artist to paint Amor Vincit Omnia for the artistic patron the nobleman, when he was finally becoming almost respectable with prestigious ecclesiastical projects? This profane non-Christian god revives the sexual provocations of his early works but in a increasingly powerful, uneasy way. Half a century later, its secret seemed clear: it was a representation of the painter's lover. A British traveller saw Victorious Cupid in about 1649 and was told its subject has "the physique and countenance of [Caravaggio's|his] own boy or assistant that slept with him". The name of this adolescent was Cecco.

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