& honestly, this just makes it worse. She wasn't even the protagonist. Just a foil for her little brother which came through pretty loud and clear. What's wrong with wanting to be the hero in the story? You guys all got to be. I didn't get to be. Then he writes a girl just to show how a boy grows up. Horribly disappointing.
I fear you're missing my point (or perhaps I didn't phrase it explicitly or well enough): In a very real way, they are
doppelgängers; two sides of the same coin. Podkayne is the one we focus on, and she is much easier to like, but she lacks any degree of cynicism, necessary to survive within such an environment. Her brother, on the other hand, lacks all the "human" traits she has; he is her "shadow", so to speak, not the substance. When Podkayne dies, he has to learn to become her, in some ways, in order to survive and grow, because otherwise he himself is simply an empty shell, nothing more. Hence his taking care of the infant "fairy" -- something he simply would never have done on his own.
A part of this, too, is tied to themes which Heinlein explores in different ways in several of his books, notably
Stranger in a Strange Land,
I Will Fear No Evil, and
Beyond This Horizon: the idea of the soul or personality taking on different roles in the everlasting game of existence. As in
I Will Fear No Evil, when Podkayne dies, she reappears as a part of the one she was closest to in life (albeit, unlike that novel apparently, this is as a part lacking a separate consciousness). At least, that is how it strikes me....
In other words, she most definitely is the protagonist, but (like Victor Frankenstein and his creation) she and her brother are mirror-images of each other; neither one alone is entirely a complete human being; and if it weren't for Poddy's particular strengths, Clark too would not have survived. It is her final act of self-sacrifice (an entirely selfless act, something which he could not even conceive of) which breaks the mold and gives him a chance... but only if he learns to take on those very parts of her which are alien to his normal personality. As it is, the book leaves it somewhat ambiguous whether or not he can, in the end, do so, though there is hope in the very fact that he is stumblingly attempting to understand. In her own way, Podkayne plays the part of the protagonist much like Michael Valentine Smith does in
Stranger (where many might argue Jubal is the actual protagonist -- but it is Mike who changes Jubal and once more allows him to join the human race).