The protagonist in this movie has a complete emotional arc from confidence to breakdown and finally to rebirth.

arc 的本义是"弧线"，在这里用作比喻意义，指"情感发展变化的完整过程"。就像一条弧线有起点、顶点和终点一样，arc 用来描述人物情感或性格发展的完整轨迹。