Who is Frida from Airhead #2: Being Nikki and what is their importance?

Frida is Em's younger sister. She was the initial target for Em's accident, but Em saved her by pushing her out of the way and taking the fallout herself. Frida adores Em and is even more fascinated by her new lifestyle. Though only fourteen, Frida wants to act like her older sister and is very envious of the lifestyle Em can now lead.