
In essence, Sam Loomis and Michael Myers are a dichotomy, split from the dark void that could be condered the “isness”
of everything, where such ideals of good and evil, right or wrong, mply do not exist.
In laymen terms, they are the yin and yang of horror.
One cannot truly be without the “being”
of the other; they help each other exist, essentially.
I hate to get so esoteric here, but as it is, if you t through the whole Halloween series, you begin to notice that there are “evil” qualities in both our characters here.
There can also be “good” qualities in both.

I want to talk a little about this dichotomy and I can't think of any better way to do so, than to have help from an old friend of mine, Stephen King.
In his book, Danse Macabre, King talks a lot about the dichotomy of archetypes, namely the Apollonian and Dionyan concepts.
In specifically referring to Dr. Jekyll and Mr. Hyde, King defines this particular dichotomy, “...Apollonian (the creature of intellect, morality, and nobility... and the Dionyan (god of partying and phycal gratification; the get-down-and-boogie de of human nature)” (King 75).
Okay, so your saying to yourself, who is Sam Loomis in this tuation, because we all know that he loved to get down and boogie.
Or was he the “creature of nobility” humbly trying to take down the boogieman?
Yes, that's more like it.

Loomis is that brave and bold archetype, who knows that he is battling evil and knows also, that he has to do anything to uphold that ideal.
Michael also knows his role, as pure evil, completely self-gratifying, phycally and mentally in his need to spill blood.
King's definitions ade, what John Carpenter initially created was the epitome of good verses evil.
What we find out at the end of the original film is that, because evil can never die, so too can good never die.
We are left with the strong sensation that Loomis feels this to his core, almost that he knows that for him to exist, his counterpart must also.

Furthermore, this seeming separation of characteristics and archetypes becomes blurry when we see the both characters share milar traits.
Loomis, after years of trying to stop Michael, becomes so merciless himself that he will do anything necessary, even if it means become evil, even for just a moment.
For example, in Halloween 5: The Revenge of Michael Myers, Loomis uses Jamie as bait to lure Michael in to a trap, essentially risking her life in the process.

Ok, so the question of the day is how is Michael inherently ever “good”?
Okay, ready for the long shot?
Here is it:
Michael, you know, the guy who kills anyone who gets in his way of , you know, killing?
Well, he spares the lives of children.
One is example is the little boy who asks so innocently, “are you a giant?”
in Rob Zombie's Halloween II.
I'm going to go even further on a limb and say that, in actuality, he spared his niece Jamie's life as well.
If you follow along with the story, it's the trait of his evil that he wants to be handed down to Jamie, through pasng his urge to kill at the end of Halloween 4, to the telepathic connection in Halloween 5, to the unnerving offspring brought about in Halloween: The Curse of Michael Myers.
He lets her live until she becomes an adult.
Michael understands innocence, something he cherishes and is under the deluon that he still is such a thing as innocent.

In the end, Loomis and Michael are both true oppotes existing to keep the other in existence, and at the same time their nature molds into each other blending and fermenting until a minute characteristic seen only in one becomes a major turning point in the anomaly of the other.
Please feel free to discuss, I am open to all opinions as long as they are justified by mine (I suck at sarcasm)...

Source:
King, Stephen.
Danse Macabre.
Berkley Book, 1981.