Demacia needs a "Dark Warrior" in its roster

With Riven being the "on the level" character among the Noxians (so to speak), I think Demacia needs at least one character who straddles the line between good and evil. Vayne is pretty close, yes, but her lore hasn't really shown off just how zealous she is toward hunting dark mages. Would she be willing to harm innocents? Who knows?

Anyone wish to chime in on this thought?