In one of the potted medical histories that punctuate his book, William Fiennes recounts how, in 1862, the neurologist John Hughlings Jackson began work at the National Hospital for the Relief and Cure of the Paralysed and Epileptic in London. "Wishing to escape 'the great vagueness of the word epilepsy', Jackson wrote detailed descriptions of hundreds of his patients' seizures: jerks and twitches, dreamy states, sensory hallucinations, the momentary inability to move a limb or understand words." After a decade of such studies, Jackson concluded: "There wasn't just one disease, epilepsy, but many epilepsies." One cannot help thinking that this should have been a decisive moment in our understanding of this condition, and in purely medical terms, it was. Yet, as Fiennes's astute and tender account of his brother Richard's epilepsy demonstrates, we still have a long way to go.
Richard is a wonderfully vivid character: by turns foolish, sweet, aggressive, confused, hopelessly irritating yet possessed of an odd, gawky charm, he moves through the book like a force of nature, tearing around on his racing bike, chattering endlessly about football (everything he owns is emblazoned with the blue and gold Leeds United insignia), smashing windows in a violent rage that he forgets almost the moment it is over and, sometimes, with some unexpected gesture or turn of phrase, filling the lives of those around him with a strange magic. "She's like red roses, shining, in a way," he says of his psychologist, in wondering appreciation; at a birthday party, with the whole family assembled around him, he recites one of Belloc's cautionary tales, impromptu and from memory, with "the whole table's attention focused on him, his eyes twinkling with candlepoints".
Yet, as charming, lyrical and childlike as he can be, it is a mark of Fiennes's integrity as a writer that Richard also comes across as something of a bore, on his better days, and as frighteningly aggressive, even dangerous, on his worst. Throughout, there are references to Richard's habit of laying his hand - "the Bible weight we were all familiar with" - on someone's shoulders as he launches into a long spiel about Leeds United; his violent behaviour - assaults on staff at the care centre where he spends much of his time, dark threats and furious rampages that cause terror and havoc at home - is never glossed over. Richard is, quite simply, a very sick young man and, as his illness progresses, he will have to endure encounters with the police, expulsion from the care centre and an array of mind-altering drugs that, while they allow some control over his seizures, induce amnesiac fugues, extreme lethargy and moments of heartstopping carelessness.
Yet, in spite of all this, Fiennes, 10 years younger and significantly smaller and weaker than his brother, cannot "think of Richard's personality as a set of symptoms; I couldn't think of his character as a manifestation of disease. That would have implied the existence of an ideal healthy Richard my brother was an imperfection of, a dream-Richard this actual person couldn't measure up against. But there wasn't any other Richard."
This, perhaps, is why The Music Room is not a study of epilepsy, as such: that would have involved taking Richard out of his natural element and holding him up as some kind of specimen, and Fiennes is after something altogether more interesting. To begin with, I wasn't sure what this was, as it seemed as if Fiennes had two books on the go - one a gentle, English country house memoir - but these two strands wind together to fine effect as the book progresses. In fact, The Music Room defies categorisation: part family romance, part historical investigation, it is, at its heart, an inquiry into how fundamentally we are defined by the duties of care that we assume or inherit: care of the land, care of a house, care of ourselves, or care of a difficult and sometimes dangerous son and brother.
Fiennes's mother and father are the custodians, not only of their children - one of whom, Thomas, dies in early childhood - but of an "estate passed down through my father's ancestors since the 14th century", an estate which includes a moated castle and extensive parklands, the castle open to the public and the park a focal point and attraction for the local community and for film crews, who flit through from time to time, shooting historical dramas such as Joseph Andrews and The Scarlet Pimpernel.
The portrait of Fiennes's parents is wonderful: patient, stoical, perplexed, quietly heroic, they get on with things, only rarely allowing their pain and bewilderment to show through:
One afternoon I saw Dad standing next to the house, his right arm stretched out, palm pressed flat against a buttress, his head dropped. He didn't move.
"What are you doing?" I asked.
He said he was asking the house for some of its strength.
This scene comes after a particularly violent outburst, during which Richard menaces his parents and brother with an iron bar and smashes the kitchen windows, his rage only abating when the "two explosions" have "shocked the fury out of him". Later, he will sleep; later still he will repent, but he will soon forget what he has done, and the next time he lashes out it will be just as violent and just as bewildering.
Nevertheless, this is not the whole story, and the family continue to grasp at every straw: the moments of warmth and joyful appreciation, the little acts of kindness and grace, the beguiling turns of phrase that reveal Richard's subjectivity, the soul that lives inside the mass of symptoms and side-effects. This is no misery memoir - on the contrary, it is a thoughtful and lyrical account of an extraordinary childhood - yet reading The Music Room one cannot help but be awed by the depth and persistence of the love this family feels for their damaged brother and son, and by their ability to live so fully and so gladly with their burden. Life goes on: the house and grounds must be maintained, visitors are shown "through the Great Hall, down the Long Gallery, into the King's Chamber, Council Chamber, Queen Anne's Room, Great Parlour and Chapel", the heron flits here and there in the dusk, a constant, grey, dreamlike presence and, gradually, Fiennes sees that "my childhood was a temporary predicament, and that as soon as I was old enough I'd be able to make my own way. I knew that autonomy was only a matter of time. But for Richard there was no such prospect of loosened constraints, no country of self-determination on the horizon. His childlikeness was indefinite. He was moated in."
That Fiennes is an unusually skilled writer is already evidenced by The Snow Geese, a work in which, time and time again, he conveys not only the incandescence of life in the quotidian flow of events, but also the richness of the idea of home, a richness that is, perhaps, only fully appreciated after long absence. At the end of that book, he returns to the family estate, passing through the named, familiar fields - Little Quarters, Morby's Close, the Shoulder of Mutton, the Great Ground - crossing the Sor Brook and following the single-track road past Danvers Meadow, where sheep are grazing and rooks are calling from the great trees in the park. And, just as we cannot help sharing in that richness, a blessed sense of place that is not proprietorial, but celebratory, so a similar, though rather different, celebration informs the closing pages of The Music Room
"We are rich in what we have lost," Fiennes's mother says, after her epileptic son dies - and we sense the celebratory intent in her words. But we also sense, as she repeats them, an unsettling ambiguity: a wishful identification with the son whose name they have always abbreviated to "Rich", but also a recognition of the inevitable if partial relief of having lost the burden she and her husband have carried so patiently for so long and even, perhaps, a recognition that such a loss finally affords the carers of this difficult, fascinating, oddly beautiful man an opportunity to stand back and see him at his best.
Similarly, the book offers a final glimpse of him singing the old anthem "Lead Me, Lord" at a Christmas gathering: "Nobody moves. The piano begins, and as the moment approaches for Rich to start singing he's like a diver gathering himself on the high board, chest expanded, on the brink of open air. We all hold our breaths as he breathes in."
• John Burnside's Glister is published by Jonathan Cape. To order The Music Room for £13.99 with free UK p&p call Guardian book service on 0330 333 6846.
