Board Thread:Lore Discussion/@comment-16323332-20140410210836/@comment-16047389-20140411151153

I would say that that is the most likely theory on size differentiation in this game: Power equals height.

In any case, From is going in on the stand point that the current game is canon regardless of choice made in Dark Souls 1. I believe that more undead arrive after the Chosen Undead to link the First Flame in a never ending cycle. So whether the Link the Fire or the Darklord ending were taken is irrelevant, as more undead just made sure that the Age of Fire continued anyway.

My point I'm making with the above statement, is that Vendrick can't be the Chosen Undead, as that would infer that the Darklord ending is canon.