Rose is the commander of Rat Army who is disordered and nervous. That’s pretty much all we know about him. (Actually, we also find out that he's Jewish.) When Ender joins Rat Army, Rose is a nice change of pace from Bonzo in Salamander Army, but Ender doesn’t learn much from Rose. In fact, Ender learns more from the toon leader Dink who teaches him not to be like Rose. So, Rose is useful…as a bad role model. (Though not as bad a role model as Bonzo.) For instance, Rose lets the game get to him, whereas Ender…well, Ender knows it’s just a game. But does Ender let the game get to him?