And often, such was the communion in which they lived, the strength of Buck's gaze would draw John Thornton's head around, and he would return the gaze, without speech, his heart shining out of his eyes as Buck's heart shone out.
For a long time after his rescue, Buck did not like Thornton to get out of his sight.

From the moment he left the tent to when he entered it again, Buck would follow at his heels.

His transient masters since he had come into the Northland had bred in him a fear that no master could be permanent.

He was afraid that Thornton would pass out of his life as Perrault and Francois and the Scotch half-breed had passed out.

Even in the night, in his dreams, he was haunted by this fear.