One of the Six God-Generals, Asch is the original Luke fon Fabre. After being kidnapped by Van, he is replaced by a replica, while he joins the knights under the alias "Asch". He originally goes along with Van until he begins to hate replicas, especially Luke, who has his identity. Asch assaults Luke several times during the early hours of the game. After a certain point in the game, the player can control him from time to time. Asch also occasionally helps the group on later occasions, though he mostly prefers working alone, while keeping his deep hatred for "the replica", Luke. According to Asch, his name is a play on the ashes of the "Holy Flame" that Luke's name represents. He's extremely short tempered and is even more impulsive then Luke.
Source from Wikipeida