Because everyone's always telling old Prince Aleksander of Hohenberg how important he is, we're going to let him take a backseat for now and discuss Deryn Sharp first. Ha. And boy, is Deryn Sharp somebody we would want on our side in a fight.
Here's the number one thing to know about Deryn: She loves the sky. She loves it so much she's willing to change her name to Dylan and pretend to be a boy just so she can get into the British Air Service. That's hardcore. She lies about her age too, but that's kind of minor compared to the whole gender switcharoo one. The necessity of lying about who she is makes her even more anxious to prove herself, which comes out sometimes in her internal monologue:
Hey, all you sods! I can fly and you can't! A natural airman, in case you haven't noticed. And in conclusion, I'd like to add that I'm a girl and you can all get stuffed! (4.43)
We should mention here too, that Deryn is really good at her job. She's so good at it that when the Leviathan has to drop midshipmen in order to pick up Dr. Barlow and Tazza and all Dr. Barlow's stuff, Deryn is one of only two who is chosen to remain on board. And remember: This, from someone who whose age and gender technically exclude her from even being there in the first place.
Deryn is extremely compassionate—not that this makes her any less of a midshipman—and she hates to see anyone get hurt, and is even willing put herself in danger to keep it from happening. When Mr. Rigby is shot in the first battle, Deryn hurls herself into thin air to keep him and Mr. Newkirk safely aboard. Her compassion also comes out in the way Deryn talks to the beasties, and in her concern for them after the wreck:
The men—not the fabricated creatures. Did he mean taking the beasties' food? But surely he wasn't saying… (27.45)
We see Deryn at her most compassionate after she discovers who Alek is and that his parents were murdered. She doesn't see him as His Serene Highness, but as her friend. She tells him:
"You're more than just that, though […] You're the one who came across the ice to save my bum from frostbite." (35.59)
Deryn is more interested in who Alek is on the inside than in anything else about him, and she can empathize with his loss because, while we don't yet know what exactly happened to her Da, we know he is also dead. Let's just say that we think that soft spot Deryn has for Alek is only going to get bigger, because now she's totally got a raging crush on him—and of course, he thinks she's a boy. Face palm.