 It signifies that the individual is closest to Apocalypse in terms of power, and it also means that the individual leads Clan Akkaba in Apocalypse's absence/hibernation.To achieve the title one would have to undergo many tests and trials and ultimately battle any who questioned them and their rank.The inner Council of Clan Akkaba were the leaders of the clan and those showing great skill or possessing enough of Apocalypse's blood to be next in line or challenge the fittest for his/her title.