Big Mama had raised you as her own, even if you were the TMNT's long lost sister ever since Lou Jitsu left you behind. Baron Draxum gave you to Big Mama as a baby and now here you are, fighting in the battle Nexus every single day for your mother. Even if Big Mama didn't usually show it, she cared deeply for you like her own child. She would never let anything bad happen to you.