Demandred is Taim. Killed Asmodean because he could expose him. Showed up very conviently when Rand arrived in Camylen (just after Asmodean died). In a conversation with Rand refers to the Aiel as "these so-called Aiel" which is exactly the phrase used by the other Chosen earlier in the books. It would be interesting if it was Demandred who said it eariler in the books. I can't be bothered looking up the page numbers.