One of the things that never ceases to amaze me about Fullmetal Alchemist is the veritable wellspring of depth and emotion behind the characters, their actions, and motivations. Each character has clearly defined (if not always correct) reasons for what they do, and their essential humanity is expressed in each and every decision they make. There is also something to be said for the archetypal themes and contexts presented by the show, most of which lie beneath the surface and can be difficult to explain or to understand.
-Edward Elric and Redemption of a Dream-
Edward Elric is the archetypical hero on a quest. Just as any other hero (Beowulf, Odysseus and even Hamlet), he has a journey to undertake and several hurdles to overcome before he reaches his goal. Of the three characters mentioned I would associate him most closely with Hamlet, mainly because, like Hamlet, Edward feels responsible for the terrible events which have occured in his life and feels that only he can right the wrongs. Hamlet attempts to kill his step-father in revenge for the murder of his real father. Edward attempts to regain his brother's body, lost through their own childish mistake. Each hero has something they feel they must accomplish, whether their reasons are for revenge or redemption, and the road is never easy. The interesting thing about Edward is the path he seems to be taking later in the series. While most heroes will undergo a period of questioning (such as Hamlet's famous "To die; or not to die" soliloquy in which he considers suicide), and then continue towards their goal, Edward Elric appears to be giving up on his goal of redemption. When Roy asks him if there is something more important than his dreams, Ed replies that there are always things like that. If Ed is referring to the fact that the Philosopher's Stone is an evil which must be removed from the world so the wrong kind of people (like Dante) won't be able to use it for their own selfish purposes, then he can only be considering one thing-
Destroying it. And killing his little brother in the process. If I'm right about Ed's motivations and subsequent actions, this will mark his growth into a mature adult. Putting aside his own dreams for the sake of innocent people he's never met is the ultimate act of selflessness, and Edward's sacrifice will elevate him above the level of mere hero to martyr. This may not solve all their problems - in fact, the world will most definately continue to have problems whether the stone is present or not - but at least Ed is taking a step in the right direction. Ed had already proven that he can move beyond his dreams and do what must be done by killing Sloth, who bore the face of his mother. He even went so far as to dig up her grave in order to destroy the homonculus. I believe that the destruction of his own sin precedes the destruction of sin incarnate, which is manifested by the Philosopher's Stone. Death, War and Vengence create the stone and hence the stone is sin itself. It is fitting that manifestations of Dante's seven deadly sins are its caretakers and guardians.
-The Seven Deadly Sins and Dante-
Which brings me to the sins themselves. In Dante's Inferno, damned souls are judged according to their actions and relegated to the level of Hell appropiate to their crime. Circle 3 is for the lustful; Circle 4 the gluttons (I don't think it a coincidence that Hagaren's Lust and Gluttony share such a close a bond; in Hell they would have been neighbors); Circle 5 the avaricious (or envious); Circle 6 the wrathful; Circle 7 the violent; Circle 8 the hypocrites, makers of discord, theives, etc; Circle 9, the treacherous. The very lowest level is reserved for Satan. It is not unfounded to say that Hagaren's personifications of the Sins possess abilities proportionate to their manifestation, as has already been explained by another member of this community. Dante could be interpreted as both the creator of the sins (as Dante Alighieri, author of The Divine Comedy), or as Satan, he (or she) who controls them.
-The Gate and the Circle of Creation-
The Gate and the recurring theme of equivalent trade are intriguing concepts in and of themselves, but combined with the alternate reality (OUR reality) which can be found on the other side of the gate, they become more than intriguing - they become essential to understanding all the underlying themes of the series. The lives of those who die in war on our side of the gate are transferred to energy to fuel Alchemic transmutations in Ed and Al's world... This begs the question, what about the energy of the lives taken on their side of the gate? With no Alchemy, are their lives perhaps used to further our own scientific and mechanical advances? In this way, is our mutual destruction also a force of creation? By destroying lives on our side of the Gate we allow creation to occur on the other, and perhaps vice versa. If this is the case, then all creativity and creation is spawned by death and destruction in a never-ending cycle. Is this the root of mankind's inclination to destroy? Without destruction there can be no creation. This law of nature has already been proven scientifically in the case of the life-cycle. Upon death our bodies are broken down and re-used to nurture life in the form of plants, the animals which eat them, and so on. The theory of an alternate dimension which acts as the polar opposite of our own - creation for destruction, destruction for creation - becomes much more plausible in light of these observations.
(end part one, because it's making my head hurt. ^^ More to come... Roy's motivations, the uselessness of vengence, and conclusion)