Moridin is Ishamael. He doesn't remeber much because he went mad -thinking *he* was the Dark One himself-, but it seems to me only someone with Ishy's ego could have the fortitude to call himself "Death." Remember, "With the Lord of the Grave, death is not always final." Ish was too much of a heavy hitter not to come back and torture Rand some more. Aran'gar, BTW, is Bathamel! Aran'gar displays the short temper Balthamel supposedly had, and Aran'gar seems to enjoy ingratiating him/herself with women (Egwene). Idle speculation, but I think "the clues are there...