This is in response to a message you sent over a year ago, but there were no responses so I thought I'd give it a shot.There was a John Flett, a Metis from Red River colony, who was convinced by the Hudson's Bay Company (specifically, by George Simpson) to come to the Oregon Territory and settle in exchange for a contract with the newly formed Puget Sound Agricultural Company (1840s).
More than likely, as a young man Mr. Flett and his father were probably involved in the fur trade, and very likely one of them (whomever was old enough) was out West with the Northwesters. Most Metis or men married to Metis or Native women who lived at Red River were involved in the fur trade or came from fur trade families.
The John Flett who came out to Oregon in the 1840s settled first at Nisqually (now Washington state), and then, as the soil was poor, moved to the Willamette Valley Oregon, possibly on the Tualatin plains (near Oregon City, OR) where the soil was better and where a fairly large Metis/French-Canadian community already resided.
If you think this is the guy, I suggest you look up a book by John Jackson called "Children of the Fur Trade" - lots of pictures etc. about the Flett family, and, for primary sources, some of Gov. George Simpson's published letters are available and mention the trip across the country and list the names of the individuals.