So because Nemo's father swam half way across the world to find him and because father's don't get the best deal on Buffy, Nemo is the antisthesis of Buffy?
I'm afraid I'm really not seeing this hun. If you use that reasoning then ALOT of shows/films/books will become the antithesis of Buffy.
I wouldn't also agree so much that father's get a raw deal on Buffy, the message was more that you make your own family because the one you're born into doesn't always work out.