Hey,
@Jordan M Tetley , you wrote:
" The Antagonist is one who doesn’t want a bridge. So in other words, he wasn’t to take down the Bridge who is dividing the plains. Plains being the real world and the afterlife. So I need to find a reason why he would want to do that? Like winning a loved one back, like thinking the plains should be the same thing? Can a simple idea in that retrospect work? "
And the answer(s) is: Yes, yes, and yes!
You answered your own question - if the Protagonist is trying to DO something - to BE the bridge, so to speak - then the antagonist needs to stop them. The story DEMANDS that there’s a force or person working against them, either directly or indirectly. They need to butt heads every now and then, or at least the Bridge/Protagonist needs to come across the villain’s "influence" in the world - some challenge for them to overcome. Ultimately, there needs to be a showdown of their ideals at the end - the climax - from which only one of them will walk away.
So, yes, FIND A REASON for the villain to oppose the hero, and you’re set. Now, it can’t just be a mustache-twirler "I’m evil just because" kind of character. Those are very, very boring. The reason the bad guy does what he does has to be something readers can identify with - we don’t necessarily have to agree with it - but on a deep level we can relate to it, we can in some small way see ourselves wanting to do the same thing if we were in his/her situation.
For my own book "The Animal in Man" - I actually designed the villain first. (And give him a frikkin cool name - Salastragore - which I’m kinda proud of...!) My whole story started as a D&D campaign a loooooong time ago, so I didn’t even know who the Player-characters would be, but I KNEW already who they would be fighting against. I had his whole backstory, and all his plans were sewn into the campaign, so no matter who my players chose to play, they would be encountering either him, his agents, or his influence throughout their story. That’s just how my story took shape, kind of backwards, by designing the world and the villain first. Most stories, I’d wager, start on the ’right’ foot and think in terms of who the hero is, and how they’re going to leave their footprint on the world as they move through it.
Once you have figured out what kind of villain you have, you have to give him a reason. If he just wants chaos, what’s the reason for that? If he’s more complicated and is trying to do the "right" thing, how did he arrive at that conclusion?
Going into personality. Is he the type of person who would try to explain his side of things to get more people on his side? Or would he just coerce people to join him? When he comes to clash with the protagonist, is he going to just throw some fireballs and be done with it, or will this hurt him to do so?