During his life, Rose alternated between residing with Native American tribes and working on behalf of commercial fur trapping expeditions funded by Eastern companies.
Much of Rose's early life is obscure, but it is known that "he was a half breed"[1] and "his color was not far from that of the savage; black hair, changeable eyes, and a fiendish expression of countenance, when he chose it, with a little paint, gave him the appearance of a natural born Indian.
"[2][3] Historians believe that he worked along parts of the Mississippi River, ranging between Illinois and New Orleans, and that when he was young, he lived among the Crow Indians, adopting their heritage, language, religions, and customs.
[6] By the time he reached the age of eighteen, he was known to have participated in robberies and fights in the city The scars and visible signs of his brawling inspired the Crow to call him Nez Coupé, or "Cut Nose.
Upon his return to camp, likely in July 1808, Rose came into conflict with Lisa over the misuse of trade goods,[7] leading to a physical altercation between the two men.
[8] Expedition member John Potts attempted to intervene, but it reportedly took ten or fifteen men to prevent Rose from firing on the fleeing Lisa with a swivel gun.
In the years that followed, Rose was equally content to live among the Crow or among mountain men, meeting with both groups to work as an explorer and trapper.
[9] After a days-long trading negotiation with a group of Crows at Crazy Woman Creek ended without success, Hunt suspected Rose had been disloyal and blamed him for the failure.
For two days, the groups maintained distance and avoided conflict, but when a few members of Ashley's expedition, including Rose, ventured into the Arikara village, a skirmish broke out and one of the trappers was killed.
The next morning, Arikara warriors attacked the camp and opened fire on the trappers, killing 15 and wounding 9, forcing the expedition to flee downriver.
Rose facilitated horse trading along the way, and successfully negotiated with the Crows for passage through South Pass to the Green River beaver grounds.