Rosalind is an interesting character. Significantly, as a woman in a niece's position at court, she takes a secondary role to Celia who is the dominant one of the pair while at court. Once the girls reach Arden Forest and Rosalind is in the guise of the youth Ganymede, Rosalind becomes dominant and her dominance is enhanced when she finally acts in the spirit of the daughter of Duke Senior (which doesn't occur until the end of the play).
I pray thee, Rosalind, sweet my coz, be merry.
Dear Celia, I show more mirth than I am mistress of;
and would you yet I were merrier? (I.ii)
Thus one contrast in traits as niece and daughter emerges from the basic premise of the play. Though loved by her devoted cousin Celia, as a niece at court Rosalind is secondary; she is the penniless relative being given shelter, food and education out of pity and charity (rather much in the same situation as Fanny in Jane Austen's Mansfield Park). As a daughter, as the heir of the rightful ruler Duke Senior, she is assertive, masterly, dominant, the natural authority who resolves conflicts and is expectant of being obeyed.
Other traits that emerge--excluding traits that are relevant to Rosalind's transformation to Ganymede, who is more direct, more inter-relational, more self-initiating than Rosalind, in fact, more the hero than the hero--in Rosalind as a niece are compliance, despondency, fearfulness, melancholy, pessimism. Other traits that emerge in Rosalind as a daughter are confidence, decisiveness, acuity of perception and thought, reasonableness, optimism, independence.
The summary of these contrasting traits, these contrasting roles as niece and daughter, is that while in a niece's role, Rosalind is representative of her place as the daughter of an exile, the dislodged heir to a kingdom, and the recipient of a grudging charity and kindness (Celia is the only genuine source of love and kindness in Rosalind's experience as a niece in Duke Frederick's court). Yet, while in a daughter's role, Rosalind enters the realm of rightful authority, peace maker, resolution giver, just judge, and the recipient of honor, devotion and love from all quarters. In other words, she if out of her right place and not her genuine self in her role as a niece while she in her right place and demonstrative of her true self as a true ruler in her role as a daughter.
I will marry you, if ever I marry woman, and I'll be
I will satisfy you, if ever I satisfied man, and you
shall be married to-morrow:
I will content you, if what pleases you contents
you, and you shall be married to-morrow. (V.ii)