Rowson's characterization of Montraville is more nuanced than it initially seems
"What am I about? . Though I cannot marry Charlotte, I cannot be villain enough to forsake her, nor must I dare to trifle with the heart of Julia Franklin. I will return this box . which has been the source of so much uneasiness already, and in the evening pay a visit to my poor melancholy Charlotte, and endeavour to forget this fascinating Julia."
In Chapter I, the young captain appears to be a dashing womanizer with no regard for the consequences of his actions. While before, Montraville proclaimed himself someone who "never think of the future" (4), he is now determined to treat Charlotte as honorably as possible, even though he can't marry her. Montraville's good intentions add a layer of complexity to his character while also enhancing the realism of the story, since few young women would voluntarily elope with a man who was obviously evil and did not care for them.
“That I loved my seducer is but too true! yet powerful as that passion is when operating in a young heart glowing with sensibility, it never would have conquered my affection to you, my beloved parents, had I not been encouraged, nay, urged to take the fatally imprudent step, by one of my own sex, who, under the mask of friendship, drew me on to ruin.”
Excerpted from Charlotte's letter to her mother in Chapter XXII, this quote illustrates her (and Rowson's) continuing tendency to blame others for Charlotte's downfall. In this case, Rowson emphasizes the role that a bad female role model can play in encouraging other young women to "take the fatally imprudent step." Although the author frequently seems 
to assume her readers are young, innocent women, there are indications in the text that she anticipates a wider readership as well.