Rosen is a student who spent his youth studying somnetics under his father. He doesn't have much passion for anything in life, and wants to spend his days lazing about with nobody bothering him. After some time had passed with no apparent change in his attitude, his mother and father collectively decide to oust him from their home and stop his tutelage. They tell him not to come back until he makes something of himself, and so Rosen decides that he would like to gain the power to never have to be bothered by anybody ever again.

Rosen is a Feyline; he is a quiet, standoffish youth who tries his best to blend in with the background. He prefers not drawing attention to himself when able, and he tends to avoid direct confrontation unless it is absolutely required. He is very hesitant when it comes to making decisions, and often finds himself deferring to others when deciding what to do.

When he finds himself in conflicts, he would prefer to resolve them as quickly as possible. At times, he is willing to get his hands dirty for the sake of his personal peace.