Laciel is the first playable character in the game, as part of Lucio's dream. In the dream, Laciel is trying to find his sister. As he is part of a dream sequence, his level starts at 40 and he cannot equip/unequip items. In the end, Laciel will fight the Devil, and Lucio snaps out of the dream.
For most of the game, Laciel is a mystery, and Lucio only has Laciel's Gauntlets. It is revealed later on, however, that Lucio is in fact Laciel's reincarnation. Lydia, who was Laciel's Sword Sheath, somehow survived to the present day despite having a reincarnation of her own in Ameli.