Non person oposition

I have read some books where the opposition was not a person but they where by highly experienced authors. If you are still learning or having trouble then stick to making the opposition a character.
if you chose to omit a person who is in oposition to Buck's motives, then the easiest form to make the story is an eposotic form, where the story is made up of a series of short plots. one little asignment after another that add up to the big assignment.
 a hostile setting, or culture, a desese, society at large, nature, any thing that is personlike counts as a character. buck in opposition to himself counts as a character.