The Hive are said to come from another dimension (nether realms) which we cannot fully understand yet. This comes from the Crota grimoire cards detailing how we couldn't damage him until we traveled to the source of his being. While they are contemporaries of the darkness I feel they were drawn here by its presence rather than being controlled or directly tied to it. Crota also may not necessarily be Oryx's son; this was the closest translation possible and may actually be mistranslated. The Hive are fascinating.