Isobel was born to Mr. and Mrs. Ross, a wizard and witch, and grew up in a village in Scotland alongside many Muggles. When she was eleven, she went to attend Hogwarts School of Witchcraft and Wizardry, but her Muggle neighbours believed she had been sent off to an exclusive all-girls boarding school in England. During her time at Hogwarts she excelled in Charms, graduating top of her class in the subject. She was also Captain of the school Quidditch team.
At some point during her teens, Isobel became romantically involved with Robert McGonagall, a Muggle who lived in the same village. However, since she knew her parents would disapprove of the relationship, she kept it a secret from them.
Marriage and family
Deeply in love, Isobel (then aged eighteen) and Robert decided to elope, angering both sets of parents. Mr. and Mrs. Ross were so upset that they completely severed ties with their daughter. On the honeymoon, Isobel could not bear to tell her new husband she was a witch, and so the fact remained a secret.
Isobel moved with Robert to a manse on the edge of Caithness. She proved skilled at making the most of the small income he earned as a Presbyterian minister.
The couple's first child, a daughter, arrived on 4 October, 1935. Isobel, missing her family and the magical world she left behind in the name of love, named the baby Minerva in honour of her own grandmother, a powerful witch. The residents of Caithness found this name extremely unusual and Reverend McGonagall found it very difficult to explain to the members of his congregation why Isobel had chosen it.
After Minerva's birth, Isobel became moody, alarming her husband. When Robert consulted his friends, they told him that post-partum depression was not uncommon for new mothers to go through, and that it would soon pass. However, Isobel only grew more withdrawn, sometimes hiding away with Minerva for days on end.
What Isobel was actually trying to do was keep Robert from catching sight of any of the subtle signs of being magic that Minerva had displayed from her very first hours of life. One night, she finally broke down under her husband's gentle questioning, and, in tears, retrieved her wand from where it was hidden and showed him she was a witch. Robert, while shocked by this revelation, did not love Isobel any less after it. Isobel also explained how she was bound to keep the existence of the wizarding world secret from Muggles by International Statute of Wizarding Secrecy.
While the couple still loved each other afterward, they never regained the sense of trust they once shared, something which Minerva, an extremely bright, observant child, recognised.
Isobel and her husband eventually welcomed two more children: Malcolm and Robert Jr.. In time, both proved to be magical, and Minerva readily helped her mother teach them that they could not go around showing off their magical powers, and helped her cover up the accidents their magic sometimes caused.
Isobel wept when Minerva's Hogwarts acceptance letter came, not only from pride, but envy. While Minerva was closest to her father due to their similarities in temperament, she sympathized with the difficulty her mother faced in having to blend into an all-Muggle village, and in being apart from other people like herself and having to restrain the use of her powers.
Magical abilities and skills
- Charms: Isobel graduated top of her Charms class and hence must have been very proficient in this area of magic.
- Flight: Isobel was a Quidditch Captain and therefore must have been an excellent flyer.
- Pottermore (Mentioned only)