Lucius is a secondary character in Fire Emblem and makes minor appearences in the DLC and Spotpass content in Fire Emblem: Awakening.
Lucius is an effeminate monk who joins Lyn during the fight against the Black Fang, and stays with her until the defeat of Lundgren. It is later revealed he was a retainer of House Cornwell until the houses demise, and now follows one of its only remaining members, Raymond, now under the name Raven. Lucius acts as Raven's conscience, urging him to drop his vendetta aginst those he believes responsible for the destruction of his house. Lucius's effeminate appearence and nature is a running joke among the fandom.