It looks like this has already been pretty thoroughly addressed, but I just wanted to say it really weirded me out when I realized Terra was "supposed" to be blonde after she had been so solidly driven into my head as having green hair. I haven't played Dissidia yet, but I'll be getting her alt green hair asap when I do. Not to get too far off topic, but it feels like a lot of characters in the early FF games ~officially~ have blonde hair (or hair that is light and ambiguously colored)...I like them better with their varied crazy hair. Variety is the spice of life! And the fact that such a high percentage are blonde kind of kills the "blondes are meant to be exotic" argument for me personally, in respect to the FF world. Celes wasn't supposed to be exotic (...right??), but she was given blonde rather than the average brown hair. I'd believe "Amano is a blondophile" over the exotic thing, even if the exotic argument is true of Japan itself...but as for the switch to green, yeah, I think it's to keep her separate from Celes (even if their outfits seemed distinct to me) and because green is more otherworldly than blonde.

Or maybe Terra just went swimming in too much chlorine water, idek. One of those.