What Happens When You Mess With the Original Novel

After possessing a piteous side character in a novel who is fated to die, Seraphie doesn't waste any time lamenting her fate. Instead, she sets out immediately to change the original plot and save herself from an untimely end at the hands of her abusive father. She'll stop at nothing to save herself from any bit of suffering, even if it means messing with the lives of the main characters. But is it really that easy to change a story's plot? Or are some things just destined to happen?