Isam was a small child or baby when Malkier fell and was lost with his mother, who had been married to Lan's father's brother, and who been instrumental in fatally weakening Malkier to make the nation vulnerable. Luc was the son of the Queen of Andor, in much the same position as Gawyn - he would be his sister's First Prince of the Sword when she took the throne. Both he & his sister Tigraine were the subjects of the attention of their mother's Aes Sedai advisor, Gitara Moroso, who had the Foretelling. She is believed to be responsible for the disappearance to Luc into the Blight and Tigraine's disappearance shortly after, leaving behind her husband, Tarangail(Moiraine's brother), and son, Galad. The Queen died shortly after her children's disappearance, leading to Morgase taking the throne and marrying Tarangail, and raising Tigraine's son, and touching off the Aiel War. It is unknown what transpired when Luc went into the Blight, or how Isam grew to manhood there (though the prologue of tGS suggests how he survived). In any event, the two men presumably fought, but the end result was they somehow ended up combining into one entity that could switch between personas. That entity, referred to as Slayer by the wolves and readers, can travel to & from Tel'Aran'Rhiod in the flesh, and take the aspect of either man. When he does change, he appears to either become the other man entirely, or at least assume the persona of the other one. He appears to still think of himself as Luc when he is in the Luc persona, and knows of Luc's blood-relationship to Rand, thinking of Rand as "his nephew." However, that is fairly meaningless, as the context of that identification included a wish to have killed "his nephew." He serves the Shadow, as well as possibly others who "beg" for his services, as an assassin, obeying the Dark One and the Forsaken, and also commanding Shadowspawn. He appears to have been the one who brought the Trollocs to the Two Rivers in tSR, with the intention of carrying out a standing mission to find and kill Padan Fain (mentioned by Moridin in WH), as seen by Lord Luc's interest in whether or not Fain survived the destruciton of Taren Ferry. He is also known to have been charged by one of the Forsaken with the assassination of Rand in Far Madding, and to have killed the Joiya Byir & Amico Nagoyin in the dungeons of the Stone of Tear during the Trolloc attack in tSR. Some suspect him of killing Asmodean, due to his presumptive familiarity with the out-of-the-way places for an ambush in the Royal Palace (where he would have grown up) and his often being mistaken for Lan in his Isam persona (and thus being someone Asmodean would recognize).