The Idoneth Deepkin are a cursed people. When Teclis took his due of Aelven souls from the captive Slaanesh he crafted a new race that he hoped would embody the virtues of the Aelves from the world that was. He failed. The creatures he created were not untainted by their time within the God of Excess, holding within themselves a deep well of darkness. Horrified at his failure, Teclis attempted to eradicate his newly created children but could not act before they fled, far into the deepest oceans of the Ethersea. There they multiplied only to discover to their horror that the majority of their children possessed withered souls. Few survived beyond birth and fewer still to adulthood so a decision was made. In order to safeguard the lives of those few children that survived the Idoneth would need to graft healthy souls to theirs thus do the Idoneth venture into the mortal realms on raids to enslave living captives to be donors and ensure the future of their race.