Eloisa was born in 1817 at Fort William, Ontario. Her mother, Marguerite, was the daughter of a Swiss fur trader and a First Nations woman whose name is unknown. Her father, Dr. John McLoughlin, was a rising star in the North West Company, a fur trading organization that rivaled the powerful Hudson's Bay Company. At the time of her birth, Eloisa joined an already-large family - she would likely have known three half-sisters from her mother's previous marriage (a half-brother from this marriage was already in the Pacific Northwest), a half-brother from her father's first marriage, older brother John, Jr., and older sister Eliza. The family would be completed in 1821 with the birth of Eloisa's younger brother, David.
John and Marguerite McLoughlin were not officially married until 1842, when Catholic missionaries to Fort Vancouver performed the service. However, their informal marriage, though not sanctified by church or state. was a dedicated one. Despite long periods of absence because of his work, McLoughlin always returned to Marguerite and their children.
In 1821, the North West Company had effectively been absorbed by the Hudson's Bay Company in a merger that McLoughlin himself had helped negotiate in London. McLoughlin was promoted to "Chief Factor," then sent to the Pacific Northwest to establish Hudson's Bay Company operations in the region. A spot was chosen on the north bank of the Columbia River, and Fort Vancouver was built and christened in 1824.
Eloisa, then seven years old, her brother David, and her mother made the overland journey from Fort William to Vancouver with their father. Elder siblings John, Jr., and Eliza remained in eastern Canada, where they were to attend school.
Coming of age at Fort Vancouver
In an account of her life, Eloisa described life at Fort Vancouver as isolating and cloistered. Though they lived in the fort's most comfortable accommodations, the Chief Factor's family was kept separate from the fort's many employees and visitors. In the Chief Factor's House, the families - women in particular - ate in a separate mess, while McLoughlin held court int he house's central mess hall. Eloisa stated, "The families lived separate and private entirely. Gentlemen who came trading to the Fort never saw the family. We never saw anybody."
A notable exception came with the arrival of American missionaries to the fort. Dr. Marcus Whitman, who arrived at the fort in 1836 while preparing to establish a mission near Walla Walla, Washington, dined in the ladies' mess along with his wife, Narcissa. In her journal, Narcissa Whitman described the nineteen-year-old Eloisa as "quite an interesting young lady."
As Eloisa approached a marriageable age, she first drew the attention of fur trader Francis Ermatinger, a Hudson's Bay Company clerk with extensive field experience. Ermatinger began his appeals to McLoughlin for his daughter's hand as early as the winter of 1831-32. Though he described her as a "fine Girl" who had "improved much by the company of the Ladies from England and America," Ermatinger's letters intermingle his desire to marry into the McLoughlin family with his interest in furthering his career and settling down after living the peripatetic life of a fur trader. After asking repeatedly, Ermatinger received his final refusal from McLoughlin in 1838. Ermatinger attributed his failure to the fact that he was too old for Eloisa (he was nineteen years her senior). At the time of that final defeat, Ermatinger wrote in a letter to his brother it was clear who Eloisa's husband was to be: William Glen Rae.