Buck begins to form a bond with Thornton. The bond is built completely on love. Buck and Thornton express love for each other daily with their interactions throughout the day.
In spite the love Buck showed for John he still had strain of primitive. He hears calls from the forest telling him to go into the forest. He thinks about this but stays due to the love he has for John.
Buck saves John's life at a bar when he was struck by a man and he attacks the man. Once Thornton was struck Buck instantly sprung out lunging for his neck. He tried two times to get the neck he was beat by clubs in order to get off of the man with that his reputation was made.
Buck saves John's life once again when he was poling-boat. They had hit a bad spot and the boat tipped over and John was washed downstream in wild water which no swimmer could live. Buck sprung out towards John, John grabbed his tail and Buck paddled with all his might towards shore. He couldn't reach the shore with John to he took a rope and climbed on shore with it while Hans, Pete, and Thornton grabbed on and pulled away from the bank.
John places a bet that Buck can break out and start 1000 pounds. Buck harnesses up and begins to tug on the huge load. Little by little the cracking of the sled becomes snapping and the load budges. Slowly he begins to tug to the 100 yard mark