Answer:
Conflict.
Step-by-step explanation:
In any story, the character's dealings with the situations that come along his way determines what his future will be. One of the most important problems that a character must overcome is that of conflict. It can be any type of conflict, be it within his own self, between his personality and his beliefs. But this conflict can also be him against other characters, or even against the society that he's in. It could also be against the very natural world, where the elements of nature pose a threat to his own accomplishment.