what does Adelaide find attractive about Aether, especially compared to her childhood crush on Nat?

Comparing Adelaide's attraction to Nat & Aether, I think apart from the few character traits that they share (like self-confidence and competency), the similarities lie in the narrative level of reflecting who Adelaide is at the time and what she thinks she needs. That is, Adelaide wouldn't have had any interest in Aether if they had met in high school (beyond, perhaps, a charged rivalry), and she wouldn't have any interest in Nat if they met now. But because of when their lives intersected, Nat represents for her safety and security and happiness, and Aether represents a means to that happy ending, which is appealing in its own right.

As for her attraction to Aether specifically (separate from me projecting), there's an extent to which it's predicated on self-recognition: Aether is a person Adelaide could very easily herself become. So, like, their verbal sparring and doublespeak and the veneer of gentility and plausible deniability in their conversations are all super alluring to Adelaide because she knows this game and she knows how to play it and she thinks she's good at it.

At the same time, she's envious of how... easy it seems for Aether: her ability to make inauthenticity seem authentic, when Adelaide is like perpetually one bad conversation away from shutting/breaking down. It's a game she knows, yes, but it's exhausting, and there's an appeal in the possibility of just... giving in, in many different senses.

And the last part of it is just like the pure power. Adelaide doesn't have any clue how important Aether is in within the Daybreak Corporation, but she's the face of the company for her, the company that she's staked escaping Harborview on. And Adelaide's own, personal interest in power is... narrower than I think many characters in her archetype. It's important to me that Adelaide maintains her magic as a means to an end, and not as an end in and of itself: there's a reason I chose callousness for her and not any of the other temptations like glory or addiction or even power. If it meant she got out of Harborview tomorrow, she'd give it all up. If she ever does get out of Harborview, I doubt she'd ever use magic again.

But Aether seems to her to just pursue power for power's sake, and that's both hot in a 'morally compromised sub' kinda way and useful for someone trying to escape a very powerful magical binding.