I am currently working on a dramatic story. It takes place in an entirely fictional world that I made myself. The story revolves around 2 people, one man, one woman. The two are unknowingly [at first], descendants of 2 different gods. The man, the descendant of a demon god. The woman, the descendant of a warrior god. The gods have opposed each other since the beginning of time and to this day, they fight each other using humans as proxies. Before the man and woman's destined fight, they fall in love, but are eventually forced to fight each other when the gods decide to possess their bodies directly. The woman ends up killing her loved one and the story ends there. That is about the gist of it. Of course, there is more to explain, but I don't want to confuse anyone and I don't want to present ALL of my plot elements until someone is actually interested in the above summary.

The thing about Gods is people tend to spend more time proclaiming them than actually explaining what they are.

It's kind of sad really, it kind of turns Gods into plot holes and Deus Ex Machina all at the same time.

But, if it were up to me to write this story, I'd put the two opposing Gods as part of the life cycle, like birth and death.

So one is young eternally and the other can never die.

Sort of create a kind of creepy paradoxial relationship that causes the Gods to intervene, destroying the life cycle forever.
Then start the game from there by creating a lovechild out to set things right by killing zombie babies.