What are three examples Buck shows love for Thorton ?

1) Buck gets a chance to prove his love when John Thornton interferes in a bar fight between "Black" Burton and a tenderfoot. Buck nearly kills the instigator, and suddenly he has a reputation in every camp in Alaska.

2) When John falls into the rapids of a river, Buck aids Hans and Pete in rescuing him and breaks three ribs.

3) Later that winter in Dawson, Buck wins a $1600 bet for his master by pulling a sled loaded with a thousand pounds of flour. After that Buck becomes the most famous dog in Alaska. All who see it are astounded, and a man offers to buy him from John Thornton for 1200 dollars, but Thornton doesn't blink before he refuses.

John Thornton didn't just save Buck from Hal and his beatings, he is the ideal master. His dogs are his children. John talks to them for long periods of time. He grasps Buck's head and rests his own upon it. It is almost as if he understand what Buck says to him. But Buck does not seek these tokens of affection. He is content to adore from a distance. At times he does not want to let John out of his sight, fearing that he will lose him as he has lost other masters.