There is no real porper reason I'm talking about this, but I just liked this topic, and I'd like to know what other fans think.
Please note I've just started the Krane series (right now I'm on Book#1) so I'll only be talking about whatever I know.
There dynamic is odd, but I'd say it's like a lot of real life sibling too. Sadie and Carter have said again and again how they find each other annoying and dumb. But if anyone of them needs help, the other rushes to the reause.
One example of Carter helping Sadie(and is so far, my favorite sibling part), is when in the 1st book, Sadie is stuck as Kite and is panicking, as this is the 2nd time she's got stuck and she'd hardly managed to get out Kite-form the 1st time. Carter understood was was going through Sadie's mind, he knew how it felt to be stuck, but he'd managed to form back to a human. Carter sat down with Kite-Sadie and just talked - Calming Sadie down with silly, super embarrassing stories, like how he screamed like girl one time when he found a scorpion in his sock. Sadie slowly stopped to panic and listened. This helps her come back human form. Sadie later says in her POV that she wasn't tempted to tease Carter about any of the stories she heard, infact, she was sightly grateful for the help. This, I'd say, is huge; Sadie always says how 'lizard-brain' her brother is, but in those pages, she very happy for the help.
Outside, to anyone else, they'll always say, “Gods, he's/she's annoying,” but inside, really inside, they care for each other deeply. This and many other parts show this hidden care they have for each other.
I may write more about their dynamic later, as I read more books, but I'm not so sure.
I just wanted to share my view to other fans, and see their thoughts; If you want to share you views, please add them in the comments! :)
I hope this was useful in some way to anyone!