Making the audience NOT feel sympathy for a character but still telling his story?

Hello!

I'm writing a webcomic with a novel-esque plot, and this is my first time planning any sort of story, so I'd like some advice.

Basically, there's an entire world colonized by humans that is threatened by an alien species that uses the humans of that world as cannon fodder for their own wars. The main gang go to fight the Big Bad behind all this.

The impact character, in this case the main character's best friend/brother figure, eventually turns out to BE the Big Bad that they're fighting. Time travel is involved, it's an older version of him. The reason he switches sides halfway through is that he has a confrontation with a member of this opposing species (in his own mind) who tells him something along the lines of 'these humans are the only ones who can fight against this new thing that is threatening everything in existence. Either they fight or everything dies.' Coupling this realization with a newly harbored grudge against humanity (for different reasons), he switches sides and eventually becomes the Main Big Bad Guy.

This confrontation is very important, a turning point in his life and contains the biggest decision he has had to make in his entire life. The problem is, I don't want the audience to sympathize with him after he changes, so I cannot SHOW the confrontation, which really seems to rob him of a lot of visual character development, as well as some important piece of story. If he were the main character, I'd show it anyway and let this become a story of 'main character changes sides and had to deal with everyone now opposing him', but he's not, so the impact character's story needs to take a backseat to the main storyline.

How do I make the audience understand what happened, but not sympathize with him? Preferably without using cheesy flashbacks in an over-talky scene where he's reminiscing about his past?

Response: Just to clarify that I'm understanding you...

So your main character is fighting to stop humans from being sent by the aliens to fight against an enemy who is a third faction/species. The villain is a future version of the main character's best friend who, at some point in the future, experiences a conversion in which he becomes aware of the threat. After this, he travels back in time to mobilize the humans and aliens alike into a force that can defeat the third party.

Assuming this is correct, here's how I see it...

If the 3rd faction represents a real threat, then your Big Bad is actually the protagonist who is leading the effort to achieve the Story Goal (eliminating the threat). He may be doing a good thing for the wrong reason, but that's okay.

The real antagonist is the 3rd faction (or its leaders).

Your main character is the contagonist, who is driven to delay and hinder the protagonist. (This is perfectly fine. The main character does not have to be the protagonist.) This suggests the main character may be doing the wrong thing for the right reason (perhaps he's a pacifist or doesn't want to see humans abused). This actually amounts to a very nice thematic argument in which the reader has to weigh up who's right and who's wrong.

Now on to your question...

Your main character by definition is character through whose eyes the reader sees the story. But you are considering switching to the Big Bad's point of view in order to reveal his motives, and you're worried this might make him sympathetic.

It's true that giving the reader a chance to see that the Big Bad might have understandable reasons for doing what he is doing might create a little sympathy. But a little sympathy is actually a good way to add depth to the character.

You can easily limit the amount of sympathy by doing what I suggest above -- making clear that he is doing the right thing for the wrong reason. Perhaps show that he wants to defeat the 3rd party for his own self-interest and that he is willing to callously sacrifice innocent lives to achieve this end.

This would create an interesting situation for the main character. If and when he learns more about this 3rd party, he would have to decide if "the enemy of my enemy is my friend," and who the real enemy is. Can he find a solution that saves lives and gets the support of his former friend? Or does he have to eventually defeat them both?

I think the Big Bad is in a good position to also be the impact character, since he can influence the main character because of their friendship.

Of course, there are other possible configurations. You could decide that the story goal is to save lives (in which case, perhaps the 3rd party is not a real threat after all). In that case, the main character would be the protagonist and the Big Bad the antagonist. But then the Big Bad might need a slightly different but still selfish reason for attacking the 3rd party.

Nonetheless, I don't see why you can't show the Big Bad's conversion scene. In a graphic story, this could be far more interesting than just mentioning the conversion in passing.