PRE-RAPHAELITE art’s popular image is a three-quarter-length figure in an ornate frame, probably a woman in historical costume, frozen in a mannered pose. But “Rossetti’s Portraits” at the Holburne Museum, in Bath, bathes the Brotherhood’s output in a new light, with a timeline spanning Florence Nightingale’s return from the Crimea and developments in photography and symbolist painting, foreshadowing art in the 20th century.

Throughout his career, Gabriel Rossetti produced intimate portraits of the people closest to him. At the beginning of the movement in 1848, the Pre-Raphaelites exchanged portraits of each other as tokens of their friendship, even depicting each other in the act of portrait-painting. And casting friends and family in the role of historical or mythological figures saved on the cost of hiring models.

In the first painting Rossetti exhibited with the initials PRB, standing for the Brotherhood, The Girlhood of the Virgin Mary, the artist painted his sister Christina as Mary and his mother as St Anne. A stone altar, an organ, and embroidery symbolise his family’s High Church affiliations.

Painted a decade later, St Catherine, one of the two explicitly religious works in “Rossetti’s Portraits”, shows his future wife Elizabeth Siddal as St Catherine, in golden medieval dress, carrying a palm to symbolise her faith, and a spiked wheel to represent her martyrdom. The canvas is bisected by the edge of an easel, and in the right plane a painter in a red-fringed gown and pointed shoes applies brush to board, taking down the likeness of the saint.

At the beginning of the 1860s, Rossetti created stained-glass-window designs while working for William Morris. The ink-on-paper drawing for the Sermon on the Mount for All Saints’, Selsey, casts members of Rossetti’s circle in fitting roles: his sister Christina is once again the Virgin Mary, the figure of Christ is George Meredith, St Peter is William Morris, and Judas is the art-dealer Ernest Gambart, whom the artist despised. St Mary Magdalene may be Fanny Cornforth, the model/sitter who overlapped with Siddal in Rossetti’s oeuvre and affections. The central figure of Christ towers over his seated followers, the base of his flowing robes melting in the clothing of those around him. Apart from the Virgin Mary, whose head is covered, luxuriant, flowing hair frames all the figures.

Awareness of the blurred line between model and sitter is critical in Rossetti’s work. Models were seen as a means to an end, and not the focus of the work itself. But a sitter is the subject of the painting, and the artist sets out to capture their appearance, status, and character. And the correspondence between the real woman and the subject that she represents adds another layer of meaning. Rossetti’s subject paintings can be read as portraits or performance, as biography, or historical and fictional re-enactment.

One of the most moving portraits of Siddal is from the summer of 1854, when she and Rossetti stayed in Hastings, for Siddal to recover from a bout of ill-health. The pen-and-ink drawing captures the convalescent standing by a window, her palm flat against the sill, with one side of her face and dress bathed in light, the other in shadow intensifying to blackness. Fine lines form the base of her dress, chiaroscuro creating the illusion of folds and pleats and volume.

© Society of Antiquaries of London: Kelmscott ManorBlue Silk Dress (Jane Morris), Dante Gabriel Rossetti, 1868

Two years after Siddal died, Rossetti used studies and drawings created earlier to paint Beata Beatrice in oil, where the artist’s wife stands for Dante’s love Beatrice. Both women died young. The chronology of the 1864 work is a little hazy, as the artist starts to mention it to a patron the year before “I found these sketches of my late wife.”

Fanny Cornforth, whom Rossetti drew 40 times over 16 years, features in his seminal work Bocca Baciata (The Kissed Mouth), a turning point where the artist moves away from Arthurian themes and the style of medieval religious Florentine paintings, to the oils of 16th-century Venetian old masters. Gone is the rigidity and flatness of previous works, and in their place a more sensuous feel, with dazzling light, fluid brushwork.

In the Blue Bower, the last major oil-painting featuring Cornforth, the inspiration from 16th-century Venetian painting is clear, with warm tones and shallow perspective. The background wall of tiles with Chinese motif and Arabic form, show the vogue for Orientalism, but also pushes the figure forward to meet the viewer’s gaze. The work marks the beginning of the Aesthetic Movement, and a focus on the power of beauty on the spectator.

In the mid-1860s, Rossetti entered an all-consuming obsession with Jane Morris, the wife of William. Blue Silk Dress is one of Rossetti’s few formal paintings in oil, and defies the conventions of Victorian portraiture, showing Jane Morris leaning forward with a curved back, turning towards the viewer as if momentarily distracted from the open book in front of her. Her hands are twisted inwards, as if waiting to take the weight of her chin. A vase of full-blown white roses showcases Rossetti’s skill at still life.

The Holburne’s show ends with amazingly modern-looking portrait photographs of Jane Morris, taken in 1865 in Rossetti’s Cheyne Walk home by a commercial photographer. Directed by the artist, the sitter’s experimental poses break Victorian decorum by highlighting her curved back, and showing her leaning into the lens. Careful arrangement of her clothes, to catch the light, give the black-and-white images the solidity of sculpture. As with so much of “Rossetti’s Portraits”, forms are merged and distinctions are blurred, to create something new and unsettling.

“Rossetti’s Portraits” is at the Holburne Museum, Great Pulteney Street, Bath, BA2 4DB, until 9 January. Phone 01225 388569. www.holburne.org