Lautrec of Carim quest. In the Undead Parish, you will encounter Knight Lautrec of Carim in the upper floor of a Church, which you will be able to unlock him from with a key on the same floor.

The Black Eye Orb is found on the corpse of Anastacia of Astoria (the Firekeeper at Firelink Shrine) should Knight Lautrec (prisoner at Undead Parish) be left alive and murder Anastacia.

So has Knight Lautrec, a fellow dressed in gold armour who I'd freed from a cell in the Undead Church – he's nowhere to be found now, but he's murdered the firekeeper who'd been sealed in her ...