Dark Mirror - Illuminates

Tahu and Kopaka dragged a protesting Takanuva to the Coliseum. Vahki guardians saluted and stepped aside to let the Toa enter. Wordlessly, they hauled Takanuva through winding corridors, finally tossing him into a cold, dark cell.

(...)

The Toa turned, surprised to find he was not alone. Hanging on the wall from chains around his wrists and ankles was a Matoran. Using the merest fraction of his Light power, Takanuva illuminated the cell. He stumbled back against the cell door in shock. The imprisoned Matoran was none other than Takua - a fact that seemed impossible, since Takanuva had been Takua before becoming a Toa.