Don't think she enjoys their sufferings - It's more like she got the point across to her adversaries.
That day when she gave that shawl full of ants to Harki Devi she asked forgiveness for doing that.
Adversaries - Nandini would be the first one to help out Harki Devi when she sees how troubled this lady is.
She will forget all that she has done to her and rush to that lady's help.
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CVs let us know that it is Nandini who is growing up in Harki Devi's home simply because they did not want the viewers to forget whose daughter she is.
Had they just wanted to tell the kahani of little girl who is married off in childhood they wouldn't have let the viewers known that it is Nandini.
They are just trying to highlight the good qualities of her parents which she inherited and how they come out even in such harsh circumstances.
She has not seen anyone going out of their way to stand up for people in trouble yet she does it she goes out of her way to help whom she cares for.She got caught while trying to help Kamili but she didnt care what happened to her but her worry was how she would help Kamili if she is locked up.She believes this is what life has handed her and she believes in battling and not running away from troubles or using back door methods like Devi ma atatcks.
All these qualities whether we accept it or not we have seen in Little Anandi and to an extent in Shiv when he was put under testing conditions.