Hee, I think you're the person I stole the phrase "tragic Shakespearean figure" from... either that or some online review. Anyway, he does have reflections of all of those characters, but in terms of setting things into motion, I'm going with Mercutio. His death could be part of what brings Carter back into the group (if it hasn't happened already)... or his death could be part of what sets up The Machine as 'villain.'