During Goliath. After Deryn hurts her knee, I think there're four days when they just stay in her cabin. What went on then? We barely see any of it, and all in her perspective...
Deryn is sleeping.
This is a rare enough occasion that Alek remains in his chair for what feels like half an hour, afraid to move and wake her. Between the pain, the worry, and the buzzing abomination on her knee, she's awake almost all the time. She needs the rest.
He may need it too, but Deryn comes first.
Asleep, she looks vulnerable, closer to the girl she could have been. Still, he can see traces of Dylan in her face and even the way she lies, as if some disguises, once put on, can never completely be removed.
He's been taking care of her for the last two days: bringing her food, helping her move... anything that needs to be done. It hurts her pride, he can tell, but she knows she needs the help. Alek doesn't complain either, because that's what best friends do.
And that's all Deryn is - his best friend. At least, that's what he tells himself to deny the feelings that creep into his heart when he sees her. Feelings that are wrong, and just plain dangerous.
He thinks of his country, his parents, Volger's expectations, his entire life - and sets it against the girl sleeping restlessly across the room, a small frown creasing her forehead. It's absurd that he even has to consider this.
"I can't love you," he whispers, soft enough that she won't wake. "You know that, right?"
She doesn't answer - how could she? - but the hint of sadness that never leaves her face convinces him that she knows. They both know. Alek has always seen Providence as a force for good - guiding him along his intended destiny to save the world - but only now does he understand how cruel fate can be.
No secrets. That had been their promise, and Alek thinks for a long while before he breaks it. But telling Deryn that he might - just might - be able to love her back, if he could, would do nothing but hurt them both.
In the end, he'll always be a prince, and she'll always be a commoner. There are some things that never change, and some secrets that should never be spoken.