Kingseeker Frampt is a Primordial Serpent and a friend to the Great Lord Gwyn. Since Gwyn became the fuel for the First Flame, Frampt, as Kingseeker, is looking for a successor to prolong the Age of Fire.
Frampt appears in Firelink Shrine after the chosen Undead rings both Bells of Awakening. Frampt tasks the Chosen Undead to travel to Anor Londo and acquire the Lordvessel, then collect powerful Souls to satiate the Lordvessel so that the Undead can take Lord Gwyn's place.
If the Undead places the Lordvessel on the Firelink Altar with the help of Kaathe instead, Frampt will become irate and leave permanently.