Balancing Acts

Su and her sister Si were given some bad news. Their Uncle has passed away. Only problem? They never knew they had an Uncle. Their Uncle was The Guardian of Light. Their father was The Guardian of Dark. With his death, the scales are now unbalanced, and the power and the charge that accompanies it must be passed on to Su and Si.

What is this power and what is this "charge"?

Welcome to the beginning of the Balancing Acts Universe