Who was Caravaggio's dark-feathered deity of love? What insights this masterpiece uncovers about the rogue artist

A young lad screams while his skull is forcefully held, a large digit pressing into his cheek as his parent's mighty hand grasps him by the throat. This moment from The Sacrifice of Isaac appears in the Florentine museum, creating unease through the artist's chilling rendition of the tormented child from the biblical account. It appears as if the patriarch, instructed by the Divine to sacrifice his offspring, could break his neck with a solitary twist. However the father's preferred method involves the silvery steel knife he grips in his other hand, prepared to slit the boy's neck. A definite aspect remains – whoever modeled as the sacrifice for this astonishing piece displayed extraordinary expressive ability. Within exists not just fear, shock and pleading in his darkened gaze but also profound grief that a guardian could abandon him so utterly.

He adopted a well-known scriptural tale and transformed it so fresh and raw that its horrors appeared to happen right in view of you

Viewing before the artwork, viewers identify this as a real countenance, an accurate depiction of a adolescent subject, because the same youth – recognizable by his disheveled hair and nearly black eyes – features in two other paintings by Caravaggio. In every case, that highly emotional face commands the composition. In Youth With a Ram, he gazes playfully from the shadows while embracing a ram. In Amor Vincit Omnia, he smirks with a hardness learned on Rome's streets, his black plumed appendages sinister, a naked adolescent running riot in a well-to-do dwelling.

Victorious Cupid, presently displayed at a London museum, constitutes one of the most embarrassing masterpieces ever painted. Viewers feel completely disoriented gazing at it. Cupid, whose arrows inspire people with frequently painful desire, is portrayed as a very tangible, vividly lit nude form, straddling overturned items that comprise stringed instruments, a musical score, plate armour and an builder's T-square. This pile of possessions echoes, deliberately, the mathematical and architectural gear strewn across the ground in Albrecht Dürer's engraving Melancholy – except in this case, the gloomy mess is caused by this smirking Cupid and the turmoil he can release.

"Love sees not with the vision, but with the mind, / And therefore is feathered Cupid depicted blind," penned Shakespeare, just prior to this painting was created around the early 1600s. But Caravaggio's god is not unseeing. He stares straight at the observer. That countenance – ironic and rosy-cheeked, looking with brazen assurance as he struts unclothed – is the identical one that shrieks in terror in Abraham's Test.

When Michelangelo Merisi da Caravaggio created his three portrayals of the identical distinctive-appearing youth in Rome at the start of the 17th century, he was the most celebrated sacred artist in a city enflamed by religious renewal. The Sacrifice of Isaac reveals why he was sought to decorate sanctuaries: he could take a scriptural story that had been depicted numerous occasions before and make it so new, so unfiltered and physical that the horror seemed to be occurring immediately before the spectator.

Yet there existed another aspect to Caravaggio, evident as quickly as he came in Rome in the cold season that ended 1592, as a painter in his initial twenties with no mentor or supporter in the urban center, only skill and boldness. Most of the paintings with which he captured the holy city's eye were everything but holy. That may be the very earliest hangs in the UK's National Gallery. A young man opens his red lips in a scream of agony: while reaching out his dirty fingers for a fruit, he has instead been attacked. Boy Bitten By a Lizard is sensuality amid poverty: observers can discern the painter's dismal room reflected in the murky waters of the transparent vase.

The adolescent wears a pink blossom in his hair – a emblem of the sex trade in early modern art. Northern Italian artists such as Titian and Palma Vecchio portrayed prostitutes holding blooms and, in a painting destroyed in the second world war but documented through images, the master represented a renowned woman prostitute, clutching a bouquet to her chest. The message of all these botanical indicators is clear: intimacy for sale.

What are we to make of the artist's erotic portrayals of youths – and of one boy in specific? It is a inquiry that has split his commentators ever since he gained mega-fame in the 1980s. The complex past reality is that the painter was not the queer hero that, for instance, the filmmaker presented on film in his twentieth-century movie about the artist, nor so entirely pious that, as some art scholars unbelievably assert, his Boy With a Basket of Fruit is actually a portrait of Christ.

His initial works indeed make explicit erotic suggestions, or including offers. It's as if Caravaggio, then a penniless youthful artist, identified with Rome's prostitutes, offering himself to live. In the Florentine gallery, with this thought in consideration, observers might turn to an additional initial work, the 1596 masterpiece Bacchus, in which the god of wine stares calmly at the spectator as he begins to untie the dark ribbon of his garment.

A several annums after the wine deity, what could have driven Caravaggio to create Amor Vincit Omnia for the art patron Vincenzo Giustiniani, when he was at last growing almost respectable with important church commissions? This unholy pagan god resurrects the sexual provocations of his initial works but in a increasingly powerful, uneasy manner. Half a century later, its hidden meaning seemed obvious: it was a representation of Caravaggio's companion. A English visitor viewed Victorious Cupid in about the mid-seventeenth century and was informed 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 annums when this account was documented.