I am debating whether my antagonist should be an I-understand-why-you-did-this bad or an I-have-no-rhyme-or-reason bad. Or somewhere in between. Also whether the antagonist and the protagonist should fall in love.
Any tips and/or comments would be greatly appreciated.
I think the kind of antagonist you have should be based off of your protagonist(s). Chiefly, you need the antagonist to be a good antagonist for your protagonist. Your protagonist needs to have reason to dislike your antagonist, or to want to fight your antagonist. What kind of antagonist do you think your protagonist would find most motivating?
As to wether or not they should fall in love, I think that depends on what kind of people they both are as well as how the plot leads them to develop. I'd wait to decide wether or not they will fall in love until after you've fully decided who your antagonist is.
I hope this is helpful. Good luck with your story!
Personally I believe that all villains should be relatable. Giving them a justifiable motive or traits that humanize them make the drama between them and the protagonist so much more compelling. Unless you're writing for a cartoon that doesn't need a lot of character depth (a good example would be Maleficent from Sleeping Beauty) I would make your villain understandable.