I heard someone mention this in a YouTube comment and it really caught my attention.
Basically, I think Midak is an Av Matoran. I know it was never confirmed or even mentioned but hear me out.
Midak was different from the other Onu Matoran, he didn't like the dark caves of Onu Koro, and preferred being out in the light.
Another coincidence, the Midak SkyBlaster (Which fires balls of light) was named after this very Matoran. Perhaps he, like Takua, lost his memory when he was placed in the Matoran pod.
Edited by Toa Keltan, Jun 14 2014 - 06:39 PM.