In chapter 6, the relationship between Buck and John Thornton grows. Their love for each other gets stronger and stronger through the events that happen in this chapter.
At the very beginning of the chapter, Buck recovers at Thornton's house. During this time together, their love grew. They both had ways of expressing love to one another. Thornton's way was to take Buck's head roughly between his hands, and resting his own head upon Buck's op and shaking him back and forth. Buck's way of showing love was biting Thornton's hand.
While Buck was with Thornton, he never let his eye off him. Which was good, because he saved his life twice. The first time was when Thornton was attacked by Burton. The second was when he was stuck in dangerous white water Rapids
Towards the end of the chapter, John Thornton bets 1,000 dollars that Buck will be able to haul one thousand pounds of flour. Surprisingly, he is able to do this.
Here, their love for each other grows exponentially. Thornton is very proud of Buck for being able to do this, and Buck is very happy that Thornton is proud of him. This is defiantly a key point in their relationship together.