The noun (or word that takes place of the noun) that the pronoun is referring to

He, you, ours, themselves

The answer is antecedent

the answer is: round.

in literature, round characters are considerably complex and experience or are subjected to unpleasant situations. as a consequence, they go through crucial sentimental and psychological development, which can cause surprise in the readers. in this case, juan's dramatic transformation is related to the adversities he meets at school.