Percy Shelley’s correction of Mary Shelley’s misspelling of “igmmatic” in the notebooks in which she scrawled the story of Frankenstein – “enigmatic o you pretty Pecksie!” he wrote – will be seen in all its glory in a new facsimile of Shelley’s handwritten text to be published in March.

Shelley wrote the draft of Frankenstein in two large notebooks over nine months, after famously being challenged by Lord Byron, along with her then lover Percy Shelley, stepsister Claire Clairmont and Byron’s personal physician John Polidori, to “each write a ghost story” in the summer of 1816 by Lake Geneva. She was 18 at the time, and continued her work on the story after returning to the UK, finishing in the spring of 1817.

Frankenstein, or The Modern Prometheus, which tells of how the scientist Victor Frankenstein brings life to a monster stitched together from human remains, was published in 1818. The original notebooks are held in the Bodleian library in Oxford.

Facebook Twitter Pinterest Part of the original manuscript of Frankenstein, as published by SP Books. Photograph: PR

The text on which most versions are based today is drawn from an 1831 edition that contains many revisions. But Jessica Nelson of SP Books, which will publish the facsimile of the notebooks next month to mark the 200th anniversary of the novel’s first release, said the aim of publication was “to give the impression to readers that they are holding the original – so you have the feeling the author gave you the notebooks”.

Shelley’s sprawling handwriting in the facsimile of her notebooks shows how the revisions slowly humanised her monster – it is first referred to as a “creature” and then becomes a “being”, while the “fangs” that Victor imagines “already grasping [his] neck” become “fingers”.

Her husband Percy Shelley – whom she married in December 1816 after the suicide of his first wife – is also shown to have cast a close eye over her work, correcting spellings and making vocabulary changes.

“In these two notebooks you can see how Percy interferes – in a good way,” said Nelson. “What’s really moving about this manuscript is that you can see the literary work mixed with something tender and emotional – literature and love inside the pages of the manuscript. Their two handwritings are very similar, which is bizarre and sweet at the same time.”

SP Books pointed to small changes, such as “smallness” becoming “minuteness”, and “I did not despair” becoming “I doubted not that I should ultimately succeed”. Percy Shelley also adds “a lustrous black” to Mary’s “hair” when she first describes Victor’s monster.

“Percy obviously encouraged Mary to find the perfect word, to avoid repetition, to find more powerful descriptions of the monster and of the characters. I feel he was really pushing her to go deeper and deeper in what she could achieve,” said Nelson.

Others have seen Percy Shelley’s changes differently: Anne K Mellor, professor of English literature and women’s studies at UCLA, writes of how his “endearments” such as “pretty Pecksie” “may be charming, but they also demonstrate that he did not regard his wife altogether seriously as an author, but rather as a lovable, teasable, and not yet fully educated schoolgirl”.

SP Books, which has already published facsimiles of texts including Jane Eyre and The Great Gatsby, will release Frankenstein in a limited run of 1,000 copies on 15 March.

“I’ve seen worse handwriting [than Shelley’s],” said Nelson, pointing in particular to the work of Proust. “When you first start to read a manuscript it is not easy, but as you get to know the handwriting it is a delight – you find a connection to the author.”