The Nikolaev Sisters were identical triplets kidnapped to study the differences in mutations in those with seemingly identical DNA. They loved to mess with their captors pretending to be one of the others. 

Nadusha didn't agree with her sisters about not using their powers for personal gain. She wanted to make this Dr. Gallitard hurt, but they were right if they didn't know what their powers were the easier it would be to escape once they were free they would burn this place to the ground.

Nikita she always found it odd that as identical triplets one of them had the ability to replicate herself. She's used her ability on multiple occasions. She's filled in for her sisters at their jobs when they wanted an extra day off. She even had one replicant go to work while she went to college.

Natascha wasn't really interested in her power the constructs never lasted so she never really saw the use. Literally the only time she found a good use for it was when some drunk moron decided he was going to force himself on her, she used her power to create a knife to threaten his jewels with it.

Dr. Galliard walked into, truthfully he didn't know which one of the sisters. "Miss Nikolaev...." Nikita interrupted him. "I'm Natascha Dr....Dr. Gallitard, Dr. Galliturd, I know it's something like that. What sick perverse pleasure will you inflict on me today in a vain attempt to convince me to do what you want? I must ask you one question. Did you ever hear of Einstein's definition of insanity? I am thinking you haven't you keep torturing us to make us do what you want but we keep refusing. So I must question your sanity. Clearly you need to see a psychotherapist. I recommend seeing a psychiatrist instead of a psychologist, because the former can prescribe the good stuff, while the latter just talks and gives you bullshit tests like the Rorschach test."