An interesting start, though you may need to give a little more thought to the age of your charatcters. A pureblood wizard like Christopher is never going to be using a word like 'Whoa'.
Also, I think we understood from your first paragraph that Daphne has azure eyes, so we don't need to be reminded in the very next sentence, and then repeatedly after that. Repetitive adjectives can quickly become annoying, so look for alternatives, such as thoughtful, caring, watery etc, as needed.
You're right - while there are a number of soul bond and HP/DG fics, there aren't any other HP/DG Soul Bond fics that I know of. Good luck with this one.
Author's response
you assume that just because he is Pureblood, he would not use slang, colloquialisms and assorted other mannerisms. On the contrary, some Purebloods in the Harry Potter books do actually use Muggle words (albeit somewhat inaccurately).
Also, I know that I don't have to describe Daphne's eyes that many times, but I do try to paint as vivid a picture of the scene as I can, and trying to find synonyms for words like "azure" is a royal pain in the behind.