i swear she has two personalities

My daughter has a dark side. It is just starting to come out but MAN is it there. And she can turn it on and off so quickly.
Today I watched as Sam took a pretzel that she was having for a snack and set it on the floor. She then proceeded to squat over the pretzel, close to it, but not right over it. Then she just sat there.
Polly, about five feet away, also just sat there, watching the pretzel.
They both know the rules. Sam does not feed Polly her snacks and is not suppose to drop them on the floor for Polly to eat. Polly knows that she does not take food out of Sam's hands.
This situation that Sam had created didn't seem to break any of the rules but neither of them was budging. Sam sat there staring at Polly out of the corner of her eye with this look that said "I dare you to come and try to get my pretzel. Come on, its right here. Mom is not looking. Just take it." But Polly did not take the bait. Eventually Sam gave up and ate the pretzel. Seconds later, after teasing and torturing her poor dog she was giving Polly kisses and hugs.
Turns it on and off so quickly. I just hope she chooses to be nice to her little sister!