The novel vividly characterized the protagonist as brave and fearless.

characterized 是动词 characterize 的过去式，characterize 由词根 character（性格、特征）和动词后缀 -ize（使...化）组成，意思是"刻画...的特征"或"描述...的特点"。在句中表示小说对主角性格特征的描述。