In 681, Constantine IV had his two brothers, Heraclius and Tiberius, mutilated and exiled and replaced them as co-emperor with his own son, Justinian II. But what if Justinian had died soon afterwards? I expect many would see his death as divine punishment for Constantine's harsh treatment of the rebellion of 681 and of his brothers. Would he be overthrown? Who could conceivably succeed him? And most importantly, could the Empire stumble into the 8th century without the many civil wars of OTL?