Fia is a Deathbed Companion, a sacred role in her homeland where a woman receives the life-warmth and vital energy of living champions, then lies with the remains of a noble departed to offer them a second chance at life. She was awakened by the guidance of grace and driven from her homeland before she could complete this rite. At Roundtable Hold, she embraces players to receive their warmth (explaining the 5% max HP debuff) while granting them a Baldachin's Blessing. Her true mission: recover both halves of the Hallowbrand (the half-wheel millipede mark imprinted on Godwyn's flesh), one found at Roundtable Hold, the other delivered by the player. Once reunited, she descended into the Deeproot Depths to lie with Godwyn's body and conceive the Rune of the Death-Prince, a mythic child destined to be the Lord of the Deathless, future Elden Lord for those who live in death.

Her conflict with D (Hunter of the Dead) is direct: D's twin brother was killed by Fia as part of her quest, and D executes vengeance by killing Fia in the room adjacent to the Elden Throne. Rogier learns of Fia's death and cannot face it. Dying, she sends a message: "I am Fia, Deathbed Companion. Hark, Roundtable. Disturb not the death of Godwyn the Exalted. We, who live humbly in death, live awaiting our Lord." Her Deathbed Charm, given to the player, is described as "the warmth I received from the champions." Those Who Live in Death whom she protects are souls condemned by a flaw in the Order, beings without fault, living in death by cosmic accident rather than sin.