Can I just say that baby!Yuuki was quite possibly the most amazing thing in the world ever? You do SUCH a good job playing a kid character. I'm honestly floored, since it's so easy to mess that up or make the kid seem unbelievable. But especially considering how young you played her de-age, I think you did a fantastic job of making her believably kid-like without making it impossible to interact with her. She was SO much fun, to play with and to stalk, so I'm super happy you did so with her. Aaah, she was adorable and I hope you can de-age her again soon. I'm also looking forward to any aftermath threads that may be afoot.
I have no crit to offer grown-up!Yuuki, as she is flawless and lovely, and I'm loving her growing CR with others as well as her established CR and complications with Zero and Kaname. You pack so much into your threads that, even if I'm not super familiar with the canon, I still feel like I can follow along and get invested in your characters.
I also think that you are fantastic with Kobato, although I know you've been struggling with her - and that much is clear given that she hasn't been as present as Yuuki. Regardless, I understand insecurities and uncertainties, but your Kobato is seriously perfect. Her bucket list entry was seriously adorable.