Now this is just a simple theory.What if the younger son beat the older son in battle.And took his eyes from him that would explain why tobi can't turn off his sharigan.And think tobi spams sharigan abilitys like hes a true uchiha hows that possible well the younger son is a senju so maby just maby the younger son saw the evil in the world and has been planing. The moons eye plan for some time.Who is to say that the elder son and younger son's fight went the way its being told.Some mite think this is crazy but some mite just ad to this theory.So if any one likes the idea then just ad a little reasoning.if you don't like just don't post nothing stupid lol have a good one