Calumny

Both Louis and Harry were musicians for roughly 5 years since they made the cut on the X-factor and were thrown into the industry at the same time. They hated each other's guts, not only because of all the competition but bc of their secret relationship in the past.

At the 2015 AMAs, Louis shares a specific photograph of Harry online, out of jealousy, and it causes great loss on Harry's part, which Harry was definitely not happy about.

~~~

"Well if you want to expose me like that, in the middle of the most important award show ever..." he tilts his head with that cocky smirk I remember so well. I can feel excitement spur in my belly but I put on my best poker face. "Why don't you show me just how much exposure you can give me tonight huh?... Strip!" I don't hesitate to do exactly what he says.

The trope is basically... lovers to enemies to friends with benefits. lol.