After The Thunder by Genell Dellin

Cotannah Chisk-Ko is ordered by her brother to return to the Nation to learn to behave like a proper young woman, but she continues her outrageous flirting and is attacked. Rescued by quiet, spiritual, Walks-With-Spirits, she finds an inner serenity with this man, and when he is unjustly accused of murder, she devotes herself to proving him innocent. Despite their differences, the two are irresistibly drawn to one another, and discover they are truly soulmates.