After the confusion and the chaos of Blighttown, Quelaag’s Domain is almost a relief. Sure, you have to immediately fight a lava-spewing spider lady, but at least you’re not constantly getting poisoned. Once Quelaag is dealt with, climb the stairs at the back of the room to ring the second Bell of Awakening.
There are no items to pick up in this area, but there is one bonfire. It’s just hidden. After ringing the second bell, head down the stairs. There’s an inactive elevator and a wall that looks like it should be a door. Hit the wall to open a path to the bonfire and this area’s two NPCs. You’ll also find a path out of here that leads to the Demon Ruins.