The warforged that Aarren's creation forges created were fully sentient, with the ability to have emotions, relationships, even to experience death; each new generation increased in sophistication and intelligence, ranging from the barely-sentient titans to the youngest versions of warforged who were fully capable of achieving advanced education and ability in magic. However, Aarren and Merrix had a disagreement over their use. Aarren felt that House Cannith had created life, and refused to see his creations used as tools. Merrix ignored him, and Aarren, feeling powerless, left. Powerful divination magics used to this day have only been able to confirm that he is still alive, not where he is.
