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

The youthful boy cries out while his skull is firmly gripped, a large digit pressing into his cheek as his father's powerful palm holds him by the neck. That moment from Abraham's Sacrifice appears in the Florentine museum, evoking distress through Caravaggio's chilling portrayal of the suffering youth from the biblical account. The painting appears as if the patriarch, instructed by God to kill his son, could snap his spinal column with a single twist. However the father's chosen method involves the metallic grey blade he grips in his other hand, prepared to cut Isaac's throat. A certain element remains – whoever posed as Isaac for this astonishing piece displayed remarkable expressive ability. Within exists not only fear, surprise and begging in his shadowed eyes but additionally deep grief that a guardian could betray him so completely.

He adopted a well-known biblical story and transformed it so fresh and visceral that its terrors seemed to happen directly in front of you

Viewing in front of the artwork, observers identify this as a actual countenance, an precise record of a young model, because the same youth – identifiable by his disheveled locks and nearly black eyes – appears in two additional paintings by Caravaggio. In each case, that highly expressive visage 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 learned on Rome's streets, his black plumed wings demonic, a naked adolescent running chaos in a well-to-do residence.

Amor Vincit Omnia, presently displayed at a British museum, constitutes one of the most discomfiting masterpieces ever created. Observers feel completely disoriented gazing at it. The god of love, whose arrows fill people with frequently agonizing longing, is shown as a very real, vividly lit unclothed figure, standing over toppled-over objects that include stringed devices, a musical score, metal armor and an builder's T-square. This heap of possessions echoes, intentionally, the geometric and construction gear scattered across the ground in Albrecht Dürer's engraving Melencolia I – save here, the melancholic disorder is caused by this grinning deity and the mayhem he can unleash.

"Love sees not with the eyes, but with the soul, / And thus is winged Love depicted blind," wrote Shakespeare, shortly before this painting was created around the early 1600s. But the painter's god is not blind. He gazes straight at you. That countenance – ironic and ruddy-faced, looking with bold assurance as he poses naked – is the identical one that screams in fear in Abraham's Test.

As the Italian master created his three images of the identical distinctive-looking kid in Rome at the dawn of the seventeenth century, he was the most celebrated sacred painter in a city ignited by Catholic renewal. The Sacrifice of Isaac reveals why he was commissioned to decorate sanctuaries: he could take a biblical story that had been portrayed numerous times previously and make it so fresh, so raw and physical that the terror seemed to be occurring directly before you.

Yet there existed another aspect to the artist, evident as quickly as he came in Rome in the winter that concluded the sixteenth century, as a artist in his early twenties with no mentor or patron in the city, just talent and audacity. The majority of the works with which he captured the holy city's attention were everything but holy. That may be the absolute earliest hangs in the UK's National Gallery. A youth opens his red mouth in a yell of agony: while reaching out his filthy digits for a cherry, he has rather been bitten. Boy Bitten By a Lizard is sensuality amid squalor: observers can discern Caravaggio's dismal chamber mirrored in the cloudy liquid of the glass container.

The boy wears a pink blossom in his hair – a emblem of the sex commerce in Renaissance art. Northern Italian artists such as Titian and Palma Vecchio depicted courtesans grasping flowers and, in a work destroyed in the WWII but documented through images, the master represented a renowned female courtesan, holding a bouquet to her chest. The meaning of all these floral indicators is obvious: sex for sale.

How are we to interpret of the artist's sensual portrayals of boys – and of a particular boy in specific? It is a inquiry that has split his commentators ever since he achieved mega-fame in the twentieth century. The complex historical reality is that the painter was not the homosexual icon that, for example, the filmmaker presented on film in his 1986 film about the artist, nor so completely pious that, as certain artistic scholars improbably assert, his Youth Holding Fruit is in fact a likeness of Jesus.

His initial works do make explicit sexual suggestions, or including offers. It's as if the painter, then a penniless young artist, identified with Rome's sex workers, selling himself to live. In the Florentine gallery, with this thought in mind, viewers might turn to an additional early creation, the 1596 masterwork Bacchus, in which the god of wine stares coolly at the spectator as he begins to undo the black ribbon of his garment.

A few years after Bacchus, what could have motivated the artist to create Victorious Cupid for the artistic patron Vincenzo Giustiniani, when he was finally becoming almost established with important ecclesiastical projects? This profane non-Christian god revives the erotic provocations of his early paintings but in a more intense, unsettling manner. Half a century later, its secret seemed clear: it was a portrait of the painter's lover. A English visitor viewed Victorious Cupid in about the mid-seventeenth century and was told its subject has "the body & face of [Caravaggio's|his] own youth or servant that laid with him". The name of this adolescent was Cecco.

The artist had been dead for about 40 years when this story was recorded.