I have an "enemies-to-???" thing going for one of the relationships in Apparent Secrets, but haven't resolved whether they'll be friends or lovers just yet.
Their first impression was terrible and didn't get better for a long time. One of them tormented a mutual friend of the other's for ages and got their just desserts when everything came to light. Is there enough redemption in the world for them to forgive each other for the mounting pile of slights and misunderstandings? [intrigue intensifies]
As for writing them, I like to give both parties a reason to dislike each other, instead of "one is an a-hole and the other is blameless." I find this helps with the push and pull of the relationship as it grows, instead of being a one-sided endeavor. Also, I'm a big fan of a gradual path to closeness. No "grand gestures" here; if they both put in the work necessary, they can grow past the initial yuck (hopefully). Ultimately, whether an enemies-to-??? happens or not, both parties in my stories need to be true to their authentic selves, which ultimately helps guide whether they have a future together as honest equals.