I think that Anderson means that grotesque is something that really
shows in a person. It is the true person. Alice is a grotesque because
she believes so strongly that the guy is going to come back to her and
it takes her forever to actually realize that he isn't. She finds
herself obsessing over the craziest things and feelings and it isn't
until the end that she realizes the truth. This is what Anderson means
of the term grotesque. When they learn the truth about themselves and
the situations they are in when it is too late.