All right, this is my first ever topic, so please be patient with me. But do let me know if I mess something up.
As you all know, from 2001 to 2006, all Matoran/Toa/Turaga affiliated with a given element shared the same eye color in the sets and in all media except for the films. However, between 2003 and 2004, the eye colors all switched, so that the same individuals had differently colored eyes depending on whether they were on Metru Nui or Mata Nui. The colors were:
Fire = Lime on Metru Nui, Pink on Mata Nui
Water = Orange on Metru Nui, Yellow on Mata Nui
Earth = Green on Metru Nui and Mata Nui both (the only color that didn’t change!)
Air = Red on Metru Nui, Lime on Mata Nui
Ice = Teal on Metru Nui, Icy Blue on Mata Nui
Stone = Dark Blue on Metru Nui, Neon Orange on Mata Nui
Then in 2006 the Inika all had the same neon green eye color, presumably attributable to their lightning powers. And from 2007-2008, everybody had lime green or neon orange eyes for some reason.
Out-of-universe, these eye color changes were obviously made for aesthetic set-design purposes (and I’ve got no problem with them, since they give MOCists about half again as many colors to work with). But in-universe, they seem really weird! Why would all the characters’ eyes change color simultaneously? My question for you all is: How would you explain this?
Personally I was content not to explain it for many years, rather just to assume that the set appearances were semi-canonical and that in-universe, the characters’ eye colors stayed the same throughout their lives, and maybe were not ever determined by element. However, coming up with elaborate headcanons to justify apparent inconsistencies in the text is much more fun than waving them away, and now one such has occurred to me: What if MU inhabitants’ eye colors change depending on the environment? Specifically, what if all the Matoran’s eye colors really did change simultaneously, as an outward manifestation of a change in “mode” adapting to the alien atmosphere and geochemistry of the Aqua Magnan environment as opposed to the environment inside the GSR? We already know the Toa are bending different elements inside the GSR as opposed to outside it (inside, everything is some kind of protodermis, while outside, the elements are really what they appear to be). So it’s not a stretch to imagine that the MU inhabitants’ mutation-prone anatomy would do some reshuffling to acclimate to the new environment, and the eye colors could be a side effect. This would also mean that once they went back to Metru Nui, their eyes would change back (and we have no evidence to contradict that AFAIK). Additionally I propose that the Onu-Matoran kept their green eyes because, living underground near the tunnels to Metru Nui as they do, they spend most of their time in an atmosphere containing mixed GSR and Aqua Magnan elements, not different enough from their home to cause a significant change in their biochemistry (This would in turn raise the question of why Midak’s eyes are still green…so maybe he only moved up to the surface relatively recently?).
As for the Mahri’s limited eye color diversity, it could be an effect of the Pit Mutation. As for why everyone has lime eyes on Karda Nui…hmm, maybe it’s an effect of being exposed to all the residual energy in Mata Nui’s power center?
Do you guys have any riffs on this headcanon, or alternative proposals, or other thoughts on this topic?