The Fool (spoilers for all RotE books, including LST)

[o0Ampy0o]

I'm afraid the idea of Sa being feminine is incorrect. I'll just quote Wintrow:
"For that matter, consider our religion. Sa, whom we men worship as Father of All, is still Sa when women call on her as Mother of All. Only in Union is there Continuity. It is only in the last few generation that we have begun to separate the halves of our whole, and divide the-"
...aaaand he was interrupted there.
And I always thought there is a connection between Sa and the first Elders El and Eda since the image of sailors calling Sa a 'he' and their wives calling Sa a 'she' is somehow similar to the image of Outislander men praising a masculine god and their women praising a goddess.
And to conclude the off-topic of gods, my guess is that Fitz was talking to Sa when he was almost lost in the Skill-pillar.

Throughout the Farseer, Tawny Man and Liveship trilogies Sa was referred to as her and she. I do not remember anyone thinking of Sa as male. I accepted Sa was female early on and if it was ever stressed how Sa was whatever depending on who was speaking it was not something important in light of other activities taking place. If Wintrow was the only character to define Sa accurately I wasn't paying as much attention when so many other characters referenced Sa as feminine. Considering that The Fool is one of the two most significant characters in this series, this dual nature of Sa you refer to was not given enough attention to lay the foundation for The Fool to be a hermaphrodite. 99% of the time Sa was referred to as feminine. Besides, a parallel to a god is not a requirement to prove or disprove the hermaphrodite argument.

Well, but my point is that this duality is mentioned in comparison with Sa who is both a male and a female and that the duality was mentioned not in connection to a pair of a White Prophet and a Catalyst but to White Prophets only.

Posting the text verbatim would help here as I only remember the subject mentioned in the context of White Prophets.

But the woman of Aslevjal was not a child.

You initially referred to this figure as a "girl" and that is distinct from "woman" used now. "...the legend tells a story of a girl who stayed young for years and years, whose hair was black..."

...the legend tells a story of a girl who stayed young for years and years, whose hair was black...

Assuming she was Prilkop, there's no contradiction to the theory that the skin color of White Prophets changes with time - or even that it changes depending on the fact if they are fullfiling their destiny of prophets. Prilkop knew he had failed his. Why is it impossible that his/her skin, hair and eyes became darker by the time when Icefyre had been self-buried in ice for decades or centures even?

The White Prophets darken as they instigate change in the world. The Fool darkened all over not just in skin or just in hair. It is unlikely that a White Prophet would develop dark hair and still have light skin. Either that figure on the island was all dark, instead of dark in hair coloring only, or that figure in the legend was not a White Prophet (and therefore could not be Prilkop).

And one more detail to the color-changing topic:
"...with the old ones, I came here. We were the last ones and we knew it. <...> Then I saw him, not white, but gold. I wondered. Then you came after him. Him I knew, at first glance".
So, for some reason, Prilkop - even recognizing the Fool as the White Prophet - was surprised to see the color of his skin had changed.

Separately and together Prilkop and The Fool talked about his coloring. Prilkop would have known from personal experience that a White Prophet darkens after going through the transformation where they are sick and shed skin several times in his lifetime. The surprise at the Fool's appearance might have been that the next White Prophet arrived having already instigated significant changes and transformed to a darker coloring than the virginal white.

Prilkop had to have been gold himself during a period of his life. It does not make sense that Prilkop would be surprised to see a gold White Prophet. Instead, it does make sense that he would be surprised that the next White Prophet had started to darken before he met him. He was relying on his inner vision foreseeing the White Prophet symbolically in his mind rather than a true representation of The Fool's features.

The White Prophets do not receive clear information. They get riddles and faint hints as to what they need to do. The Fool did not know whether he was seeking Althea, Malta or Wintrow until he found Wintrow and by then he had realized through trial and error that it was not Althea or Malta. In the end the Fool delivered a message that was not really that important compared to everything that happened as an indirect consequence of seeking Wintrow. It seems that the hints the White Prophets receive guide them down a path to a slowly clarified goal. But the goal is not the point. The process of figuring out the goal and the process of achieving the goal is the point rather than reaching the goal in and of itself. Great events unfolded as Amber looked for what ended up being Wintrow only to deliver encouragement to mentor Kennit's son. Considering everything that would not have happened if Amber had not pursued that goal, those final words said to Wintrow were just an excuse to make everything else happen. You might think that some unknown future would reveal the importance of Kennit's son but it is not revealed in this series. Looking at what did take pace we see evidence that the world changed dramatically in the process of delivering those words. Whatever becomes of Kennit's son is irrelevant. We do see what became of the world working toward that moment.

Back to Prilkop, he did not have a clear image in his mind of The Fool. In his mind he saw a White Prophet coming. All he needed to see was something recognizable enough to expect another White Prophet. Again, Prilkop had to have been gold himself at one time so he would not have thought "why isn't the White Prophet white? The source of the surprise would not be the existence of a gold White Prophet as though it was unheard of. Prilkop was a black White Prophet. He knew why he was black. He knew what made him black even though he had failed his mission. He also understood why the Pale Woman was white.