Most Daemons (even Chariots) are bound to one of the Chaos Gods. Only Daemonic characters can join units of Daemons. Furthermore, Daemonic characters can only join units that are solely composed of Daemons with the same allegiance as themselves. In addition, Daemons receive no benefit from the Inspiring Presence or Hold Your Ground! special rules, unless both they and the model with those rules are Daemons of the same allegiance.