Zas

Zas is a playable character in Fire Emblem: Shadow Dragon. He is a Dark Mage who jions Marth's army at the start of Chapter 12X, A Traitor's Worth. Unlike most characters he has no introductory scene and does not interact with Marth. Instead Malledus informs Marth at the start of the chapter that some troops want to join their ranks. Malledus is worried Zas could be a spy but Marth allows him to join anyway.