Dr. Malick's strategy (spoilers)
I'm curious about Dr. Malick's strategy in trying to execute the killer within Malcolm's mind. Or, as he says (in the extended version), "We must exterminate the rat, not the house."
Was Dr. Malick hoping to get Ed specifically to help find the killer within Malcolm's head? When Ed appears in Malcolm's body, Dr. Malick seems pleased. And as Ed started to drift back into Malcolm's subconscious (i.e., reappear at the hotel), Malick said to him, "Edward, I need your help, I need your help to finish this." So did Malick want Ed specifically? I can see how, if Malick had all of Malcolm's personalities well-documented, he would think that Ed would be the best one to help find the killer. (If so, you'd think he would've given Ed some more helpful information before Ed disappeared again. But I guess getting Ed just to understand the situation was quite a task.)
Further, did Malick think that Rhodes was the killer, and want Ed to kill Rhodes for him? Or did he not know who the killer was, and needed Ed to do some detective work? The last thing Malick said to Ed was "you have to understand, the killer cannot survive." And it seemed like when Ed got back to the hotel, he was on a mission to kill Rhodes, even if it meant dying himself, because he understood he didn't really exist (which would admittedly be kind of a drag). But Malick never told him the killer's identity (pun intended).
Basically: I know Malick's general strategy was to force all of the personalities together and make sure the evil one died. I'm just wondering what the specifics of his plan were.