This is quite charming. I have a thing for framed stories anyway, and I *love* The Princess Bride (and I'm even willing to admit that the first several times I read it, I actually *believed* the frame story), and hey, fairy tales! So, what I'm saying is, you pretty much had me from the moment I read your summary. :)
I love the idea of Severus as a kind of djinni, bound to the doll and helping Harry out of all his crises. And Severus as Yoda is too, too funny; it makes a weird sort of sense, though Yoda is much less, ah, choleric than Severus.
You did a nice job integrating all your source materials into a coherent and accessible whole, and the relationship between Harry and Severus/Kuki was well-developed.