Gender is blurred in the unreliable character of Rosario/ Matilda in The Monk. “As in The Monk, the supernatural body is a sexualized, ambiguous object (i.e., the shedevil Matilda)”. This character is introduced as a man without real clarification since “no one had ever seen his face”. However, this is portraying a woman as an imposture since Rosario is really the female Matilda, “I am a Woman… I am Matilda; You are her Beloved!”.
In addition to the blurred lines between genders in Rosario/ Matilda, there are obvious gender role reversals. Men are portrayed in a very feminine sense, not just women. For a bit of this novel Ambrosio is the weak main character that is normally seen in the female character in earlier Gothic novels, such as Matilda from The Castle of Wolfenbach. Ambrosio is seen from a “feminine” position at the start of this novel. Like a young girl who is protected to keep her virtue and innocence, Ambrosio is similarly protected and ignorant of the world and temptations due to being raised in a monastery.
Both Antonia and Ambrosio do not seem to distinguish the opposite sex, once again blurring the gender roles. Antonia does not seem to comprehend, “that there is such a thing as a Man in the world” and she “imagine(s) every body to be of the same sex with (herself)”. Because she is innocent in regard to understanding men are different from herself, this, “links the same feminine brother and sister together”.
Similar to Antonia, Ambrosio seems to forget that Matilda is a woman. This is most likely due to Matilda befriending Ambrosio as a man (Rosario) along with Ambrosio’s innocence. “It is Ambrosio’s sexual ignorance and hence ‘innocence’ that makes him vulnerable to Matilda’s seduction”. Ambrosio expressed this after seeing Matilda’s breasts by saying. “May I not safely credit her assertions? Will it not be easy for me to forget her sex and still consider her as my Friends and my disciple [?] … She strove to keep me in ignorance of her sex … She has made no attempts to rouse my slumbering passions, not has She ever conversed with me till this night on the subject of Love”. Excuses aside, Ambrosio continues to blur the lines between female and male.
In addition to Ambrosio being feminized, Raymond is also slightly feminized. When Raymond is with the Bleeding Nun, whom he thinks is his lover Agnes, “he sexually surrenders and sinks upon Agnes’s bosom, alerting the reader that another role reversal is forthcoming”. Furthermore, Raymond has “frequent fainting fits,”  which is normally seen in weak female characters in Gothic novels, not male characters.