The twin of Blue, and perhaps something more, Rouge is on a quest to kill his brother and become the most powerful mage in the Frontier. He also happens to be less of a prick than his other self, despite being the "villain" in Blue's quest. After all, he's less likely to leave an everyone else behind inside the belly of an inter-dimensional monster, and more likely to find a compromise that doesn't kill a Lord of magic and the orphans he harbors. He's also a friendlier sort, being more receptive to allies than his jerk of a brother. It almost makes one tempted to intentionally lose to Rouge in the magic duel, so you can get rid of Blue and control the more appealing Rouge instead (hint hint)

While his DL self isn't as broken as his banned twin, Rouge's own brand of tricks isn't something to sneeze at. Wielding the variety of Realm magic in his hands, he has damage, status, ID, and an especially nasty trick he can play on the mages of Middle.