Lucius left the orphanage and began to travel as a monk. He became a retainer to House Cornwell, where he met the Marquess Cornwell's child, Raymond. He served him for more than ten years, before Marquess Cornwell and his wife was assassinated for reasons unknown to them. The death of Raymond's parents prompted Raymond with feelings of vengeance. Raymond suspected Ostia for the crime, and became a mercenary under the alias 'Raven'. Lucius constantly tries to persuade his lord not to blindly take revenge on Ostia.
While on his travels, he stopped by an inn and witnessed Ninian and Nils looking for help from the innkeeper, who were thrown out. Concerned, Lucius followed them outside and they briefly accompanied Lyn on her journey to reclaim Caelin, and he departed after it was over. A year later, he was seen traveling with Raven again. They are captured and imprisoned in Castle Caelin when it is taken over by Laus' soldiers, but it is possible for the player to rescue and recruit them. If Raven's sister Priscilla talks to her brother and recruits him, he can also recruit Lucius in turn. Note that while Lyn can initiate a conversation between her and Lucius, Lucius will not join her, meaning that it is imperative that Priscilla is selected for this map.
If Lucius gets an A Support with Renault, he discovers Renault was the thief that murdered his father when he was a child, and forgives him. If Lucius should get an A Support with Raven, he convinces him not to seek revenge on Ostia, and they begin to travel together as mercenaries for hire.
In a possible ending in Fire Emblem: Rekka no Ken, Lucius starts an orphanage on the Araphen border. In Fire Emblem: Fūin no Tsurugi, Chad, Lugh and Lleu reveal that they lived in an orphanage in Araphen. During the invasion, the one they call 'Father' tried to protect the garden from the Bern soldiers, and they killed him. There is no official evidence that suggests Lucius is this ill-fated 'Father' the children recall, however it is speculated by some that he might be.
Super Smash Sisters Role
Lucius is a non-playable monk helper in Super Smash Sisters. He uses light magic like a normal monk would and can use a berserk staff to make opponents go nuts and attack each other. Katsuie disapproved his woman-like appearance.