There are a lot of unique things Dark Souls does that set it apart from its contemporaries. If you never played the PS3 exclusive Demons' Souls, or the PS5 remaster, before it then you likely had a very unique experience going through Lordran for the first time. However, for as hard as the game got a reputation for being, there is one NPC that almost breaks the rules of video games. Lautrec and Anastacia may not have an obvious link, but if you don't catch on quick enough you might find yourself locked into a very tough situation. Odds are you don't need this game to be any harder than it is, so follow this step by step guide to avoid a terrible fate.
Lautrec & Anastacia's Questline
You probably just know her as the firekeeper, but Anastacia is the one trapped behind the bars right below Firelink Shrine who is unable to speak. Firekeepers are very important in Lordran, and this one, in particular, is very valuable to you. In exchange for Firekeeper Souls, which you can find around the world, she will upgrade your Estus Flasks to restore more health, but there's far more value in her life than that.
Lautrec, on the other hand, is an NPC you can find locked in a cage of his own in the middle floor of the church in the Undead Parish, right below where you fight the Bell Gargoyles. You need to clear some debris to reveal and speak to him. The key to his cell is not far on the same floor of the church, but even if you don't find or free him, he will escape on his own and show up in Firelink after you beat the Bell Gargoyles.
At this point, you have a choice to make, although it isn't so much a choice unless you purposefully want to make the game harder for yourself. However Lautrec gets back to Firelink, he will be sitting directly across from Anastacia. The better "choice" is to kill him immediately. He's a very tough fight, especially this early in the game, so you might want to try and cheese him a bit by kicking him off the edge he's sitting by for an easy kill.
If you don't kill him and either ring the second bell of awakening down in Blighttown, or pick up a total of two Firekeeper Souls, Lautrec will murder Anastacia. This is where you'll learn that not only does she upgrade your Estus, but her life is tied to the Firelink bonfire. With her dead, you can no longer rest or level up at your primary bonfire.
All is not completely lost, though. Among the items she drops is the Black Eye Orb. If you carry this all the way to Anor Londo and use it at the front gates before the Ornstein and Smough fight, you can invade Lautrec's world to face him, along with two other NPCs helping him. Not only is this fight more difficult due to being outnumbered, but since you are an invader you won't be able to heal with your Estus Flask. Manage to beat this trio and you will pick up Anastacia's Firekeeper Soul you can use to bring her back to life and relight the Firelink bonfire.