A frequent theme is the power of love to change. The love the villain has for the hero can make them question their entire belief system. Also, there's the theme of secrecy. Since they are from opposing sides, they often have to keep their relationship a secret, which adds a lot of tension. In some fanfictions, this secrecy is what drives the plot forward, as they try to hide their feelings from their respective allies.
Well, 'Villain's Unlikely Love' is a great piece of fanfiction in this genre. In it, the villain has always been in the shadows, hating the hero. But as the story progresses, through various encounters and shared moments, the villain begins to see the hero in a different light. It shows how love can cross the boundaries of good and evil. The way the author portrays the gradual change in the villain's attitude towards the hero is really engaging.
There is also a fanfiction called 'When the Villain's Heart Melts'. Here, the heroine has a unique quality that the villain can't resist. It might be her intelligence or her ability to see good in everyone. As he gets to know her more, his feelings change from hatred (or indifference) to love. The story then follows how they deal with the fact that he's a villain and she's the heroine, which often goes against the norms of their world.
Often, it starts with the villain being intrigued by the heroine's defiance. For example, if the villain is used to everyone fearing him, the heroine's lack of fear catches his attention. This initial spark of interest can then grow into something more.
The challenges are numerous. There's the matter of loyalty. The hero has loyalty to the good side and the villain to the bad side. How can they reconcile this? Then there's the power dynamic. If the villain is more powerful, the hero might be in a vulnerable position. Also, they have different goals in life. The hero wants to save the world, while the villain may want to rule it. This disparity can cause a lot of problems in their relationship.
Of course. A hero - villain love story can be very engaging. It often challenges the readers' or viewers' perception of good and bad. Sometimes, the love between them can even lead to the redemption of the villain. They might start to question their own actions and motives because of their love for the hero, and this can create a really fascinating story arc.
Well, it could go either way. If the writer wants to create an interesting twist, Percy might be a villain in the Avengers fanfiction. But more often than not, given Percy's own heroic traits from his original story, he'd probably be a hero in the Avengers' universe, helping the Avengers fight against their common enemies.
It's the contrast. The villain is usually associated with bad things, and when they fall in love with the heroine, it's a complete change. It's like seeing two opposite poles attract.
A good example is 'Twilight'. Although Edward could be seen as having some villain - like qualities at first, he falls in love with Bella, the heroine. The story is filled with their romantic and sometimes tumultuous relationship against the backdrop of a supernatural world.