In September 1883 Stevenson suffered a great loss in the death of his old friend Mr. James Walter Ferrier (see the essay Old Mortality). In the beginning of 1884 his hopes and spirits were rudely dashed by two dangerous attacks of illness, the first occurring at Nice in January, the second at Hyères in May. Travelling slowly homewards by way of Royat, he arrived in England in July in an almost prostrate condition, and in September settled at Bournemouth. In the autumn and early winter his quarters were at Bonallie Tower, Branksome Park; in February 1885 his father bought and gave him the house at Westbourne which he called (after the famous lighthouse designed by his uncle Alan) Skerryvore. This was for the next two years and a half his home. His health, and on the whole his spirits, remained on a lower plane than before, and he was never free for many weeks together from fits of hæmorrhage and prostration. Nevertheless he was able to form new friendships and to do some of the best work of his life.
In 1885 he finished for publication two books which his illness had interrupted, the ‘Child's Garden of Verses’ and ‘Prince Otto,’ and began a highway romance called ‘The Great North Road,’ but relinquished it in order to write a second series of ‘New Arabian Nights.’ These new tales hinge about the Fenian dynamite conspiracies, of which the public mind was at this time full, and to the old elements of fantastic realism add a new element of witty and scornful criminal psychology. The incidental stories of ‘The Destroying Angel’ and ‘The Fair Cuban’ were supplied by Mrs. Stevenson. During the same period he wrote several of the personal and literary essays afterwards collected in the volume ‘Memories and Portraits;’ a succession of Christmas stories, ‘The Body Snatcher’ in the ‘Pall Mall Gazette,’ 1884; ‘Olalla’ in the ‘Court and Society Review,’ and ‘The Misadventures of John Nicholson’ in ‘Cassell's Christmas Annual,’ both for 1885; and ‘Markheim’ in ‘Unwin's Christmas Annual,’ 1886; as well as several plays in collaboration with Mr. Henley, viz. ‘Beau Austin,’ ‘Admiral Guinea,’ and ‘Robert Macaire.’ Stevenson, like almost every other imaginative writer, had built hopes of gain upon dramatic work. His money needs, in spite of help from his father, were still somewhat pressing. Until 1886 he had never earned much more than 300l. a year by his pen. But in that year came two successes which greatly increased his reputation, and with it his power to earn. These were ‘The Strange Case of Dr. Jekyll and Mr. Hyde’ and ‘Kidnapped.’ The former, founded partly on a dream, is a striking apologue of the double life of man. Published as a ‘shilling shocker,’ a form at that time in fashion, it became instantly popular; was quoted from a thousand pulpits; was translated into German, French, and Danish; and the names of its two chief characters have passed into the common stock of proverbial allusion. In ‘Kidnapped’—a boys' highland story suggested by the historical incident of the Appin murder—the adventures are scarcely less exciting than those of ‘Treasure Island,’ the elements of character-drawing subtler and farther carried, while the romance of history and the sentiment of the soil are expressed as they had hardly been expressed since Scott. The success of these two tales, both with the critics and the public, established Stevenson's position at the head of the younger English writers of his day, among whom his example encouraged an increased general attention to technical qualities of style and workmanship, as well as a reaction in favour of the novel of action and romance against the more analytic and less stimulating types of fiction then prevailing.
About this time Stevenson was occupied with studies for a short book on Wellington (after Gordon his favourite hero), intended for a series edited by Mr. Andrew Lang. This was never written, and in the winter and spring 1886–7 his chief task was one of piety to a friend, viz. the writing of a life of Fleeming Jenkin from materials supplied by the widow. In the spring of 1887 he published, under the title ‘Underwoods’ (borrowed from Ben Jonson), a collection of verses, partly English and partly Scottish, selected from the chance production of a good many years. Stevenson's poetry, written chiefly when he was too tired to write anything else, expresses as a rule the charm and power of his nature with a more slippered grace, a far less studious and perfect art, than his prose. He also prepared for publication in 1887, under the title ‘Memories and Portraits,’ a collection of essays personal and other, including an effective exposition of his own theories of romance, which he had contributed to various periodicals during preceding years.
His father's death in May 1887 broke the strongest tie which bound him to this country. His own health showed no signs of improvement; and the doctors, as a last chance of recovery, recommended some complete change of climate and mode of life. His wife's connections pointing to the west, he thought of Colorado, persuaded his mother to join them, and with his whole household—mother, wife, and stepson—sailed for New York on 17 Aug. 1887. After a short stay under the hospitable care of friends at Newport, he was persuaded, instead of going farther west, to try the climate of the Adirondack mountains for the winter. At the beginning of October the family moved accordingly to a house on Saranac Lake, and remained there until April 1888. Here he wrote for ‘Scribner's Magazine’ a series of twelve essays (published January-December 1888 and partly reprinted in ‘Across the Plains’). Some of these (‘Dreams,’ ‘Lantern Bearers,’ ‘Random Memories’) contain his best work in the mixed vein of autobiography and criticism; others (‘Pulvis et Umbra,’ ‘A Christmas Sermon’) his strongest, if not his most buoyant or inspiriting, in the ethical vein. For the same publishers he also wrote the ballad of ‘Ticonderoga’ and began the romance of ‘The Master of Ballantrae,’ of which the scene is partly laid in the country of his winter sojourn. This tragic story of fraternal hate is thought by many to take the first place among its author's romances, alike by vividness of presentment and by psychologic insight. In April Stevenson came to New York, but, soon wearying of the city, went for some weeks' boating to Manasquan on the New Jersey coast. At this time (March–May 1888), by way of ‘a little judicious levity,’ he revised and partly rewrote a farcical story drafted in the winter by his stepson, Mr. Lloyd Osbourne, ‘The Wrong Box,’ which was published in the course of the year under their joint names. The fact that the farce turns on the misadventures of a corpse caused most readers to think the levity more apparent than the judgment; but the book cannot be read without laughter.
In the meantime the family had entertained the idea of a yachting excursion in the South Seas. The romance of the Pacific had attracted Stevenson from a boy. The enterprise held out hopes of relief to his health; an American publisher (Mr. S. S. McClure) provided the means of undertaking it by an offer of 2,000l. for letters in which its course should be narrated. The result was that on 26 June 1888 the whole family set out from San Francisco on board the schooner yacht Casco (Captain Otis). They first sailed to the Marquesas, where they spent six weeks; thence to the Paumotus or Dangerous Archipelago; thence to the Tahitian group, where they again rested for several weeks, and whence they sailed northward for Hawaii. Arriving at Honolulu about the new year of 1889, they made a stay of nearly six months, during which Stevenson made several excursions, including one, which profoundly impressed him, to the leper settlement at Molokai. His journey so far having proved a source of infinite interest and enjoyment, as well as greatly improved health, Stevenson determined to prolong it. He and his party started afresh from Honolulu in June 1889 on a rough trading schooner, the Equator. Their destination was the Gilberts, a remote coral group in the western Pacific. At two of its petty capitals, Apemama and Butaritari, they made stays of about six weeks each, and at Christmas 1889 found their way again into semi-civilisation at Apia in the Samoan group.