With the strength of Lords, they challenged the Dragons. Gwyn's mighty bolts peeled apart their stone scales. The Witches weaved great firestorms. Nito unleashed a miasma of death and disease. And Seath the Scaleless betrayed his own, and the Dragons were no more.
Thus began the Age of Fire. But soon the flames will fade and only Dark will remain. Even now there are only embers, and man sees not light, but only endless nights. And amongst the living are seen, carriers of the accursed Darksign.
Yes, indeed. The Darksign brands the Undead. And in this land, the Undead are corralled and led to the north, where they are locked away, to await the end of the world... This is your fate.
Only, in the ancient legends it is stated, that one day an undead shall be chosen to leave the undead asylum, in pilgrimage, to the land of ancient lords, Lordran.
Indeed, an undead was chosen to make the pilgrimage. The Chosen Undead's journey came to an end after he retrieved the souls of lords, feeding them to the lordvessel and finally defeating the empty husk of Gwyn, The Lord of Cinder. The undead was left with two choices then, give his soul to the first flame to rekindle the Age of Fire and continue the cycle, or neglect the flame and thrust the world into the Age of Dark. He chose the latter, allowing the flame to die out and becoming The "Dark Lord".
The Age of Fire, in its final death throes long before the Chosen Undead was even born, recieved its just end with the death of whatever remained of Lord Gwyn. His desperate action of linking the bonfires,which had only succeeded in prolonging the suffering in the world, would lie dead with him. Now, under new leadership, the world can finally move forward into the Age of Darkness and perhaps recover some of what it had lost. (Cited from http://darksouls.wikidot.com/ending)
But with the link between the bonfires fading, the only things holding the world together, there is little left to rule over. The abyss was allowed free reign after the waning of the first flame, corruption gradually spreading across the lands. What remains is twisted, broken. Desperate few civilizations remain, and what do are slowly gnawed away by beasts of the abyss and the curse of the undead. Those who fail to overcome the curse become mindless beings, only shells of their former being.
Half a century has passed, and a magical bulwark against the dark has been established by the most skilled mages of the land, though there are doubts it will hold for long. Hope is fading, and the undead curse is still widespread. The holders of the accursed darksign are corralled to the north, to await the time when the dark finally takes over. Do you have what it takes to keep your humanity in check, or will you go hollow like the land you live in?