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

A youthful lad cries out as his skull is forcefully held, a massive thumb digging into his face as his father's powerful palm holds him by the throat. This scene from The Sacrifice of Isaac appears in the Uffizi Gallery, creating unease through the artist's harrowing rendition of the tormented youth from the biblical account. It seems as if the patriarch, instructed by the Divine to sacrifice his offspring, could snap his neck with a single turn. However Abraham's preferred approach involves the metallic grey knife he holds in his other hand, ready to slit Isaac's neck. A certain aspect remains – whomever modeled as the sacrifice for this breathtaking piece demonstrated extraordinary acting ability. Within exists not just fear, surprise and pleading in his shadowed eyes but additionally profound sorrow that a guardian could abandon him so utterly.

The artist took a familiar biblical story and transformed it so vibrant and raw that its horrors seemed to happen directly in front of the viewer

Standing in front of the painting, viewers recognize this as a actual face, an accurate record of a young subject, because the same youth – recognizable by his disheveled hair and nearly black eyes – features in several other paintings by Caravaggio. In each instance, that highly expressive face dominates the composition. In Youth With a Ram, he gazes mischievously from the shadows while holding a lamb. In Victorious Cupid, he grins with a hardness learned on the city's streets, his dark feathery appendages sinister, a naked adolescent running riot in a affluent dwelling.

Victorious Cupid, currently exhibited at a London museum, constitutes one of the most discomfiting masterpieces ever painted. Observers feel totally disoriented gazing at it. Cupid, whose darts inspire people with frequently agonizing longing, is portrayed as a extremely real, vividly illuminated nude form, straddling toppled-over objects that comprise musical devices, a musical score, plate armour and an architect's ruler. This heap of possessions echoes, deliberately, the mathematical and construction equipment scattered across the floor in the German master's engraving Melencolia I – save in this case, the melancholic mess is created by this grinning deity and the mayhem he can release.

"Affection sees not with the eyes, but with the mind, / And therefore is winged Love painted blind," penned the Bard, shortly before this work was produced around the early 1600s. But the painter's god is not unseeing. He gazes straight at you. That countenance – sardonic and rosy-cheeked, looking with brazen assurance as he struts unclothed – is the same one that screams in fear in Abraham's Test.

When Michelangelo Merisi da Caravaggio created his multiple portrayals of the same unusual-looking kid in Rome at the dawn of the 17th century, he was the highly acclaimed sacred painter in a metropolis enflamed by Catholic renewal. The Sacrifice of Isaac demonstrates why he was sought to adorn sanctuaries: he could adopt a scriptural story that had been portrayed numerous times previously and make it so new, so unfiltered and physical that the horror appeared to be occurring immediately in front of the spectator.

However there was a different aspect to Caravaggio, apparent as soon as he arrived in Rome in the winter that concluded 1592, as a painter in his early 20s with no teacher or supporter in the urban center, only skill and audacity. The majority of the paintings with which he captured the holy metropolis's attention were everything but devout. What could be the absolute first resides in the UK's art museum. A young man parts his red mouth in a scream of agony: while reaching out his dirty digits for a fruit, he has instead been bitten. Boy Bitten By a Lizard is eroticism amid poverty: viewers can see Caravaggio's dismal room mirrored in the murky waters of the transparent vase.

The boy sports a pink flower in his coiffure – a emblem of the erotic trade in early modern painting. Northern Italian painters such as Titian and Palma Vecchio portrayed courtesans grasping flowers and, in a painting destroyed in the second world war but documented through photographs, the master portrayed a renowned female courtesan, clutching a posy to her bosom. The message of all these botanical indicators is obvious: intimacy for sale.

How are we to interpret of Caravaggio's erotic portrayals of boys – and of one boy in specific? It is a inquiry that has divided his interpreters since he gained widespread recognition in the 1980s. The complicated historical truth is that the artist was neither the queer hero that, for instance, Derek Jarman presented on screen in his 1986 movie about the artist, nor so completely devout that, as certain artistic historians improbably assert, his Boy With a Basket of Fruit is in fact a likeness of Jesus.

His initial works indeed offer explicit sexual implications, or including offers. It's as if Caravaggio, then a destitute youthful artist, identified with the city's prostitutes, offering himself to live. In the Florentine gallery, with this thought in consideration, observers might look to an additional initial creation, the 1596 masterpiece Bacchus, in which the deity of wine gazes coolly at you as he starts to untie the black sash of his robe.

A several annums after the wine deity, what could have motivated the artist to paint Victorious Cupid for the artistic collector Vincenzo Giustiniani, when he was finally becoming nearly respectable with prestigious church projects? This profane pagan deity revives the erotic challenges of his initial works but in a increasingly powerful, unsettling way. Half a century later, its hidden meaning seemed clear: it was a portrait of the painter's companion. A English visitor viewed the painting 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 laid with him". The name of this boy was Cecco.

The painter had been dead for about 40 years when this account was documented.