Hmm maybe bond would be interesting :P

Never really THOUGHT of a bond. Hmm if there is one, I hope it's more like "bratty older sister and playful younger brother" or something, 'cause anything romantic would be weird (he looks just like his sister, plus if you go back far enough I think they're related somwhere). @.@

Its wierdddd. Cuz Kathrine and Elena look alike!

Well i believe that they get along so well because they both want the same thing and two heads are better than one so they do look good together, you know, companion wise but being good friends is not such a good idea....

I don't think there's a 'bond', but yeah, it'll be interesting.
However, if they try to make it anything romantic, I swear I'll shoot myself. That would be too weird and too much.
But I trust that the writers are not that stupid.