In "An Orphan's Fate," how does Rosario come to live as a gaucho on an estancia?

When Rosario is still a child, his stepfather nearly kills him and he runs away. He passes out, but his horse Bizco delivers him to an estancia, where an old woman heals him and takes him in. He has a talent for breaking horses with gentleness, and ends up being a valued ranch hand on the estancia.