|This profile/story complies with book canon but ignores information from Pottermore and other sources.|
His father, Thorfinn McGonagall, hailed from an old Scandinavian-Scottish family of pure-blood witches and wizards, while Morrigan McGonagall, his mother, was descended from the wizarding branches of the Urquart and MacLaughlin clans. His older sister, Minerva, had been born four years earlier.
Einar's life began with a tragedy. Three days after his birth, Einar's mother died from complications of the difficult labour, leaving his father grief-stricken and temporarily unable to care for his young daughter and newborn son.
Fortunately, Einar's maternal grandmother, Morna MacLaughlin, had come to Castle Isleif for the birth and stayed to help Thorfinn after his wife's death.
After several weeks, Thorfinn snapped out of his depression and shock and became a loving and doting father once again.
Despite the early loss of his mother, Einar's childhood was a happy one
Thorfinn was a scholarly man and taught both his children literature, languages, history, music, philosophy, and science from an early age, and Einar was an apt and eager pupil. From his father, he also learned to love, and excel at, Wizard's Chess, a game he would play all his life.
Morna, who had moved permanently to Castle Isleif to help rear her grandchildren, taught Einar the rudiments of magic and how to control himself. She also shared her love of Herbology with her grandson, and the two could often be found on long rambles along the Caithness coastline near their home.
When Morna tried to teach him to fly, however, Einar howled and demanded to be let off his grandmother's broom. Like his father, he had a fear of heights, and would always avoid broom travel when he could.
Like his parents before him, Thorfinn often took his children into nearby John o' Groats to meet other children, and when Einar grew old enough to control his strong magic, he would often venture into the villages around Castle Isleif to mix with the Muggles that fascinated him. He made several Muggle friends, and his father eventually bought a small farmhouse outside the villlage of Dunnet so that Einar could have his Muggle friends in to visit, as Castle Isleif was unsuitable for Muggles.
Thanks to his father's and grandmother's early tutelage, Einar excelled in his classes, particularly Charms, although he eventually grew frustrated with Hogwarts's Charms master, Herbert Burke, whom he found a less than outstanding teacher.
In Einar's second year, he petitioned Headmaster Armando Dippet to allow him to begin an extra tutorial with Muggle Studies teacher Charity Burbage, who was delighted to take on a young pupil so eager to explore her subject.
He became friendly with classmate Alastor Moody, a Gryffindor, after they teamed up to stop Slytherin Byron Macnair from bullying a first-year Muggle-born student, Einar casting a Melfors Jinx and Alastor a Furnunculous, leaving the hapless Macnair with a pumpkin's head covered with oozing boils—a condition it took then-matron Madam Soranus and Charms Master Herbert Burke two days to sort out. Einar's and Alastor's detention making a large batch of Boil Potion for Professor Slughorn sealed their friendship, and the summer after Alastor's mother died unexpectedly, Einar invited his depressed friend to spend a week with his family at Castle Isleif.
Einar was disgusted when young Alastor developed a serious crush on his older sister, Minerva; it would become a joke (and something of a sore spot) between them for the remainder of their Hogwarts years.
In his third year, as his father had done before him, Einar took a year's exchange at Beauxbatons Academy of Magic, eager to improve his French and to mix with the Muggles of the area. He was also keen to study under Beauxbatons's charms renowned Charms Mistress, Alphonsine Leblanc, who would become something of a mentor to the young man.
Einar joined the Wizard's Chess club in his first year at Hogwarts and won the school championship in his fourth, sixth, and seventh years. He was also a member of Hogwarts's duelling club, and made the semi-finals in his fifth year (knocked out by seventh-year and duelling champion Tom Riddle ) and the finals in his sixth and seventh years, beaten each time by his friend Alastor Moody.
At the end of his seventh year, Einar sat his N.E.W.T.s, earning Outstanding marks in Charms, Herbology, Muggle Studies, and Defence Against the Dark Arts, and "Exceeds Expectations" in Ancient Runes and Transfiguration.
After leaving school in 1948, Einar went to work for the Muggle Liaison Office in the Ministry of Magic's Department of Magical Accidents and Catastrophes as a junior liaison officer, helping senior officers clear up magical incidents involving Muggles.
He spent a gruelling year Apparating back and forth across the English Channel every weekend in order to pursue advanced studies in Charms with Professor Leblanc. It was from her he learned the difficult art of Obliviation—a practice of which his father strongly disapproved—which would eventually allow him to become a senior Muggle liaison officer at the age of 23.
As a senior officer, Einar was often called on to help manage more serious incidents involving Muggles and mages. As the 1950s wore on, he was disturbed by the increasing incidents of Muggle-baiting by pure-blood supremacists led—unbeknownst to Einar at the time—by Tom Riddle.
Thanks to his knowledge of languages and European culture, Einar was frequently involved in the Ministry's efforts to coordinate Muggle relations activities with other European magical governments, and in 1957, he spent three months in Paris working with and observing their Direction de la Coopération des Mages et Sansmagies.
Einar was impressed by the success of the French ministry's relatively laissez-faire attitude toward magical incidents involving Muggles; the French rarely turned to Obliviation, preferring to rely on a combination of Confundus charms and natural Muggle scepticism and obliviousness to magic to sort out accidents.
When, in 1968, Einar became Head of the Muggle Liaison Office, he added tight restrictions on the use of Obliviation, ensuring it was only used in circumstances where it was truly necessary to prevent a potential wide-scale breach of the International Statute of Wizarding Secrecy.
Marriage and family
On 25 June 1955, Einar married Katherine Roberts, a former Hufflepuff and Wizard's Chess afficionado he had met and started dating in his sixth year at Hogwarts.
On 18 September 1956, Einar was delighted to become a father. He was utterly smitten with his daughter, whom he and Katherine named Morrigan (after Einar's late mother) Gwyneth (after Katherine's paternal grandmother).
Like Thorfinn, Einar was a doting and devoted father, delighting in teaching his child what he knew of Muggles, Herbology, and chess.
Morrigan, however, while intelligent, was of a less scholarly bent than her father, and favoured Quidditch over Wizard's Chess, and her aunt Minerva was delighted when Morrigan helped Gryffindor House win the Hogwarts Quidditch Cup in 1971.
Einar was shocked when he discovered his sister's relationship with Albus Dumbledore, a man he had hero-worshipped after the latter's defeat of dark wizard Gellert Grindelwald. Einar eventually became comfortable with Dumbledore, however, and enjoyed Dumbledore's visits to Castle Isleif during family holidays.
Einar and Katherine moved back to Castle Isleif in 1977 to be with Thorfinn, who was suffering from a neurological ailment that made movement difficult.
First Wizarding War
Despite his support for Albus Dumbledore, Einar did not join the Order of the Phoenix during the First Wizarding War. Dumbledore had convinced him to take a background role protecting Muggles from Death-Eater attacks in his capacity as Head of the Muggle Liaison Office.
He was devastated when Thorfinn was killed in a Death-Eater ambush in Southhampton on 15 March 1979, and blamed himself, as he had been late to an appointment to help Thorfinn with a cross-Channel Side-Along Apparition. Despite his family's insistence that he was not to blame for his father's death, he would always feel that, had he been on time, he might have prevented Thorfinn's murder.
Second Wizarding War
By the advent of the Second Wizarding War, Einar had retired from the Ministry, due to the advance of the same neurological condition that had afflicted his father.
He was unable to join the Order of the Phoenix; however, he supported their cause by organising Muggle protection around Scotland and, like his father before him, penning anti-Death-Eater editorials in wizarding newspapers.
He was saddened at the death of Albus Dumbledore, and extremely concerned for his sister's safety as a known member of the Order of the Phoenix after the fall of the Ministry to Lord Voldemort.
After the war ended, Einar enjoyed his retirement with Katherine, who helped him continue to take long walks around the Caithness coastline with a charmed pushchair. He also continued to go into the village of John o'Groats to play chess with a group of Muggle retirees at a local pub, despite his increasing difficulty moving the non-magical pieces around the board.
He looked forward to the frequent visits of his daughter and her family to Castle Isleif and was eventually delighted to become a great-grandfather to three active children.
In 2017, when Minerva retired from her post as Headmistress of Hogwarts, Einar was pleased to welcome her as a permanent resident of Castle Isleif, of which he had become master after his father's death.
Einar was tall (6'2") and of medium build, with dark-blonde (later grey) hair and blue eyes.
He could frequently be seen wearing a three-piece Muggle suit rather than wizard's robes, thanks to both his job and his interest in Muggles.
Personality and traits
Einar, like his father, was outgoing and affable, with an easy smile and gentle sense of humour.
He had great affection for and interest in Muggles, and enjoyed mixing with them both for work and for pleasure.
Magical abilities and skills
- Magical power: Einar was a fairly powerful wizard, but preferred not to show off his talents.
- Charms: Einar was very gifted at charms, mastering the exceedingly tricky Memory Charm by the time he was 19 years old.
- Herbology: He enjoyed herbology and was quick to recognise rare and important magical plants, and often sent cuttings to his grandmother from wherever he was in the world.
- Duelling: Einar was an excellent duellist, reaching the semi-finals or finals of Hogwarts duelling championship on three occasions.
- Wizard's Chess: A bit of a chess prodigy, Einar won Hogwarts's Wizard's Chess championship in his fourth, sixth, and seventh years.
- Languages: Einar spoke fluent French and good German, as well as a smattering of Goblin.
- Music: Einar was a fairly good pianist and possessed an excellent baritone singing voice, which he used often at family gatherings.
Behind the Scenes
- "Einar" is from the Old Norse "Einarr, which is prominent in both Norse Mythology and in Norse history.
- "Drusus" derives from a common cognomen in Ancient Rome. 
- "Alpin" is Scottish Gaelic, meaning "white." 
References and notes: