The following consists of canon knowledge mixed with generous helpings of my own headcanon. Spoilers for Dark Souls ahead.
The Old Knight
Ah, new here aren't you, lad? Ha ha, worry not, I'm no mind-reading sorcerer, every new face around here comes from the asylum nowadays. Come, sit, warm yourself by the bonfire and rest. It's safe here…or at least, it's as safe here as anywhere will ever be in these dark times.
Me? Oh, I am but a humble old knight. Once I rode under the banner of the great lords of Anor Londo, but that is all in the past now. No need to bow, lad, I was never a great knight—my sword arm was strong, true, but I never had the brave heart of a true knight. Perhaps that's why I got to be so old, ha ha!
The Bells of Awakening? Pah, a fool's errand, that. In all the time I've been here I've seen scores of undead like you try to ring those bells. I would bet my old sword that those Bells are but rumors, made by the desperate to kindle even the spark of hope. But do not let the words of a tired old man dampen your spirits. Perhaps it will be you who is the Chosen Undead, hmm?
Your journey will no doubt take you far, lad. If you keep your wits about you, you might even see fair Anor Londo. Oh, to see the City of the Gods once more! I tell you, lad, you will see many things in your wanderings here in Lordran, but you will never see anything so glorious as Anor Londo. Great spires of ivory, shining in the light of the afternoon sun; the bridges that move up and down by artifice.
But the gods that lived in Anor Londo…no, not all the shining halls and great artifice could match their wonder. The Queen of Sunlight Gwynevere, her beauty unmatched; Lord Gwyn, the ever-wisest. And who could forget the Four Knights of Gwyn?
Did I know them, you ask? Nay, lad, I only glimpsed them from afar when I was but a young boy. But their tales—those I remember.
Stay a while and listen, lad, and have a sip of that estus. Let me tell you about Lord Gwyn's Four Knights: the greatest heroes this land ever did see…