Hey guys this is my theory on the Chosen Undead, I think in my respective opinion that the Chosen Undead is trapped in a version of hell, this is brought on by the fact that every time you die you respawn at the last rested bonfire, now unlike Dark Souls most games would send you back to the last saved point in the game, so this shows that the player is meant to pay for their sins in the trials of killing the Lords of Cinder and ringing both Bells of Awakening, so we'll start off with the character setup screen, when you create a new character the knight class is already selected, now with most games that have a character classes there isn't one already selected for you, this brings me to my first conclusion, the Chosen Undead was a part of the Lordran army and was convicted of a crime, most likely treason, this also supports the reason why you start out fully clothed and have nothing else but your starting gift and a broken sword, the broken sword was probably that of the old weapon the Undead used while in the army, so it was simply left with them until death. Now we go onto what motives the Undead would've had if they committed any sort of treason, is that they could've been helping out a family member or close friend escape from authorities or Lordran altogether, which would lead to them being finally overwhelmed by the army, this could also explain why Smough and Ornstein are paired together as a boss fight, as they could've been the ones who took down the previously alive Undead. Now we can move onto the Lords of Cinder themselves, in the beginning cutscene and story of the game it tells you how Gwyn, Nito, Izalith, the Furtive Pygmy and Seath all took down the dragons as a way to save humanity as it was, but when you go to fight the Lords of Cinder they are almost instantly hostile towards you, meaning that some sort of trauma triggered them to remember you as a result of any unforgiving crimes you may have committed. Now to wrap up this big theory we're going to go on with a BIG conclusion, now this includes why we see Velka's disciples throughout the Dark Souls franchise, since Velka is the Goddess of Sin she could be appearing to try and get you to repent for all of your committed sins and crimes, and to get the player to realize this the Lords of Cinder have to be killed as a recognition to your crimes and the wrong doing you have done. Hope you guys enjoyed and my theory on Smough and Ornstein will be coming out soon.