Board Thread:Dark Souls II/@comment-46.64.182.203-20140312230146/@comment-24679176-20140321195126

Old Dragonslayer soul description says:

" The Old Dragonslayer is reminiscent of a certain knight that appears in old legends. "

So, either this is the true Ornstein who else traveled along the Gods when they fled Anor Londo or he somehow managed to survive his battle with the Chosen Undead or, as time in Lordran is convoluted, this could be an alternte version of Ornstein whom never battled the Chosen Undead so he stayed at his post forever until Smough died and he was left alone, withering as time passed by and maybe going Hollow (Gwyn went Hollow too when he sacrificed himself to Link the Fire so its possible that a lesser bein could go hollow too) or traveled to the Abyss (hence his new dark magic) but that would mean that Heide's Flame Tower is what remains of Anor Londo.

Or he could be an impostor wearing good ol' Orny's armor.