Session 0

I'm sorry, I meant your first free aspect, the "she was ust joking, right?" one. Your high concept otherwise seems thorough.
Well this is a setting where alien life forms have been known and investigated for a long time so Academics.

You can discuss further on the relationship aspect. If there is also an age difference between Leda and Hariette, something like "if you have problems with Leda you have problems with me" can work. That can definitely be positive (a supportive speech from Hariette can give advantage to Leda, for example) or negative (even though there is nothing wrong, someone being mean to Leda can make Hariette provoked). I admit this is not a strong relationship aspect but acceptable, I'll allow it if you want to go in that direction.

"She was just joking" I'm expecting for it to be compelled in social situations. Hariette has a bit of a dark, morbid sense of humor that I think might not translate well for everyone. Though, now that I review it it doesn't seem like it would come up often, so I might want to reserve it as a stunt (Something like a +1 bonus when planning something reckless or dangerous) and come up with a more versatile aspect.

I like it as a stunt better, to be honest. Feel free to do anything, though, it is not a bad aspect, just that as you said, it won't come up often.

Academics -- that's a new skill. (New to Condensed. I was wondering what the 19th skill was. Now I know!)

Looks like Academics is common stuff, Lore is for weird and unusual stuff.

Flux, if you're okay with it I'm going to add Our Paths Crossed on Delban 6 as Hiro's relationship aspect with Dayton. They were indeed on opposite sides... but I'm thinking this was was Hiro wanted out, and while he got the drop on Dayton and his pals, he choose to not lower the boom / open fire / blast 'em. So they recognize one another and remember the incident, but haven't talked about it yet?

So, in the Fate core book, there is a stunt related to the skill Lore called Specialist:
I think your idea is similar to this one. Since we haven't though about this before and I see you have 0 on Lore so if you want to keep this Battlefield First Aid stunt and improve it further, you can change the skill rating of Lore.

Given it seems we're starting, can I leave that aspect blank and work on coming up with a replacement as we play?

Sure, only high concept, trouble, relationship aspect and skills need to be decided before the game. You can decide free aspects and stunts as we go. I've approved your character naelick, you're good to go.