Twas fate that ye servant discovered the snake in the first place. Twas destined that he would eventually discover it and its magic.
Twas fate that ye young fish would find and help our young lad in his quest for love. It was foreshadowed earlier in the tale when ye fish proclaimed that they would repay the young lad for saving their very lives
Twas fate that ye young lad, wandered upon this very kingdom where he would compete for the king's daughter's hand in marriage
Twas free will that ye young lad would decide to eat the white snake which made him possess his mythical animal powers. He chose to eat out of his overpowering curiosity.
Twas free will for ye young lad to kill his horse in order to feed the young ravens who were exiled from their home by their mother and father. He chose to kill his horse even though he did not need to.
DIE DIE DIE
Twas free will that ye young lad would ask to do the tasks to take the king's daughther as his wife. He had a choice, and chose the tasks which were impossible.