Something I've been thinking of recently (And am going to brush on a bit in the fic I'm planning) is how it was for Darling to watch Daring date a bunch of girls whilst betrothed to Apple, who she's in love with.
There's two sides of this coin. One is Darling being grateful, because it means she doesn't have to constantly see her love in romantic situations with her brother. The second, and my favourite, is Darling actually growing resentful of Daring because of it. Darling can't have Apple, she isn't allowed her for many reasons. Daring is, he's expected to have her, even, and simply doesn't have anything to do with her. Like a person who can't afford meals watching those wealthier than them throw food away like nothing. What Darling so desperately wants, craves, is forgotten about by the one who has it. She has to watch Daring go from girl to girl while the one girl who she's in love with is supposedly his. In a messed up way, she wants Daring to truly be with Apple.