Enemies to lovers starts with two people who cannot stand each other and gives them no way to escape. In short dramas the rivalry is usually professional or personal: competing heirs fighting over the same company, a lawyer facing the man she is suing, a new assistant who insulted her boss before she knew who he was. Sometimes the grudge runs deeper, with families that ruined each other a generation back.
The genre runs on banter. Every exchange is a small contest, and the short-episode format rewards sharp dialogue that ends on a cutting line or an accidental moment of closeness. Viewers enjoy the slow discovery that each lead is not who the other assumed, and the payoff when one of them finally admits it.
The difference between good and lazy entries is whether the hostility has a reason. Weak series invent a misunderstanding that one honest conversation would clear up, then refuse to let anyone have that conversation for dozens of episodes. The better ones give both sides a real grievance and a point of view worth defending, so the eventual truce feels like a change in both characters. Be wary of dramas where the so-called enmity is really just the hero bullying the heroine and calling it chemistry.