Eh. They're relationship is a funny one. Neither really holds a 'standard way of acting' around the other. Both can go from super clingy to super shy, form super extroverted to super introverted...none of it really feels out of sync. Makes it easy for fanartists since they can basically transcribe they're desires onto the pair and keep it in character relatively easily
Well they absolutely look like a couple from the start of the season 1. And they look great Nanoha on wedding dress and Fate in tuxedo,the kind of clothes their wearing really suits them it kinda shows what is their role in the family.......right!?