Ratan is a sensitive, affectionate, and idealistic girl. She accepts her lot in life with a good nature. Moreover, there is every indication that, in Tagore's story, Ratan is an "untouchable." In Indian society, untouchables (or Dalits) are often consigned to the dirtiest jobs. These untouchables often endure living under extremely unsanitary conditions. Because of their low status in Indian society, untouchables live impoverished lives. They are (like Ratan) usually illiterate because the education system discriminates against them, causing large populations of school-aged Dalits to drop out of school.
In the story, Ratan considers herself fortunate to be in the employ of the postmaster. Ratan's docile subservience is characteristic behavior for members of her caste. The text tells us that Ratan has "borne many a scolding from her master without complaint." Ratan does not consider her employer's often brusque and rude behavior strange. In fact, she accepts such ill treatment as typical of what members of her caste must endure.
Ratan does not realize (until it is too late) that the postmaster has little intention of accepting her into his family. Ratan's actions and words demonstrate her innately trusting nature. It is this nature that clouds her judgement regarding the postmaster's true character.
In the end, Ratan's idealistic and trusting nature shames the postmaster and almost prompts the latter to go back for the "lonesome waif, forsaken of the world."