Ceruleadroth was from a short-lived D&D campaign with some of my family; he didn't even make it onto the scene before the game ended.  Ceru was an elder blue wyrm, one of Tiamat's "lieutenants" and a priest of Tiamat.  (Hence the wing membranes adn the pendant.)  Originally from Io's Blood (the Council of Wyrms setting), which is where he acquired the habit of wearing jewelry.