Why Brown Dezorians?
Everyone familiar with Phantasy Star knows that Dezorians are green. Why, then, are the only two Dezorian characters in the game Phantasy Star Adventure both brown? My answer to this question is that the "Dezorians" are actually Palman-Dezorian half-breeds. The Palman blood in the "Dezorians" causes them to have brownish, Palman-like skin, whereas their other features remain basically Dezorian.
There is some support for this theory. Phantasy Star Adventure is set in the town of Carsonville on Dezoris, and Carsonville is a very special place. It is the only town in all of Phantasy Star that is shown to exist beneath a giant glass dome. It is the only town in the Phantasy Star II era (Phantasy Star Adventure is set in AW 1268) where a vehicle -- in this case a car -- is shown to be present. This is significant, as according to Phantasy Star II, vehicles such as cars were banned sometime around AW 1234. Mother Brain, therefore, must have made at least one exception to her rules for Carsonville. Carsonville is also special in that it is the only town we ever see that is inhabited by both Palmans and Dezorians.
To put it simply, Carsonville is, as my friend Naflign describes it, a "freak town." As you quickly discover while playing Phantasy Star Adventure, Carsonville itself is special, and most of the people who dwell in and around the town are unusual, as well. Given the anti-Palman sentiment expressed by the Dezorians in Phantasy Star and Phantasy Star II, it is easy to see why a Palman-Dezorian half-breed would take refuge in a place like Carsonville. The half-breed could remain on its home planet and be surrounded by people of both of its ancestries, yet it could escape the scorn it would likely receive at the hands of full-blooded Dezorians. The half-breed would likely never be looked upon as an equal by Palmans or Dezorians, but in a place like Carsonville, where the unusual is the norm, he or she could at least have a chance of having a somewhat peaceful and healthy life.
But how would a Palman-Dezorian half-breed come to exist? My idea is that Palman miners and entrepreneurs, while on business on Dezoris, would become "lonely" and take Dezorian girls as their consorts. Inevitably, some of these "relationships" would result in the girl becoming pregnant, and thus, a half-breed child would be born. The Dezorian community would probably be appalled by the union, and so the half-breed, and likely the mother as well, would be inclined to leave their home. And what place to settle could possibly be more ideal than Carsonville?
Here are some images of the brown Dezorians: