Ruining the Bloodline

I made something similar with Pokemon Akari idea I posted, but now I want to try something different. Still keeping the other idea up, but thinking of ideas to use with OC x OC or OC x Canon.

There will be two versions of this idea. They both will be the same, the only difference is who is the one traveling back in time. Male (MC) or Female (YC). Also bare with the idea, as I always state, any and all ideas can be altered a bit to make sense. 
 

A Divine being as came down to the Main Character for the story to tell them of a great danger within the past. What no one knew, was in the past, a great Evil was going to rise and take over the world. Though, a Hero came by to save everyone from it. The Hero, was the Main Character. Of course, there was no choice within the matter as if they don’t do it, all hope is lost and everyone will die. Of course, there was a warning for some reason. The Divine being told the Main Character “Whatever you do, don’t fall for your Ancestor ______” which of course, was weird to say since they think they wouldn’t. So, the Main Character took up the option to head back in time to save everyone. What they didn’t realize, was the attraction they will have with their ancestors.
 

Like I said, could be either person going back in time. Could be MC who will be a Male, or YC who will be a female. They will encounter their ancestor and a few options can happen:

Corruption: What the Main Character doesn’t realize is that their Ancestor is obsessive. Either they never got a lover before, or gone through so many bad relationships where they think this new person will be the best for them. They want the Main Character for themselves. Could even be a “Bad Ending” type where it ended up dooming everyone because of their obsessiveness.

Wholesome: Their Great Ancestor is actually an attractive and nice person to be around. They are so nice that would spark up something within their heart. Cause if everything is a repeat, then maybe the Main Character is destined to create a family with this Ancestor of theirs. Right?

Once more, up for a lot of interpretation on how we can change the story if anyone is interested ^^.