The next morning she woke up and found that someone had taken care of the fire while she slept, and her pack was lashed on one of the saddles.

She rode on that day and came at night to a camp-fire with a bed of boughs near it and no one in sight.

She took that camp for herself and no one showed up.
"Don't you see?
Someone was following her up the valley and taking care of the poor baby on the way.

Someone who was afraid to let himself be seen.

Perhaps it was the man who killed Dick Wilbur without a sound there beside the river; perhaps as Dick died he told the man who killed him about the lonely girl and this other man was white enough to help Mary.
"But all Mary ever saw of him was that second night when she thought she saw a streak of white, traveling like a galloping horse, that disappeared over a hill and into the trees--" "A streak of white--" "Yes, yes! The white horse--McGurk!" "McGurk!" repeated Pierre stupidly; then: "And you knew she would be going out to him when she left this house ?" "I knew--Pierre--don't look at me like that--I knew that it would be murder to let you cross with McGurk.