In many novels with such a premise, the 'rival' often has his own motives and backstories that lead to this situation. For example, he might have been wronged in the past and sees the hero as an obstacle to his revenge or to achieving his goals. The plot could also explore how the two characters grow and change through their rivalry, and whether they will eventually reach some sort of understanding or remain enemies.
I'm not entirely sure about this novel in particular. But often in this type of story, the 'rival' character has their own backstory that led them to become the hero's adversary. It could be that they come from a different background, like a poor upbringing while the hero is from a privileged one. This disparity might fuel their rivalry, and as the story progresses, they might either find a way to reconcile or the rivalry could escalate to a point of no return.
There could also be other supporting characters. Maybe there is a love interest that both the hero and the rival are vying for. Or there could be a mentor figure who has influenced either the hero or the rival. Another possibility is that there are sidekicks for each of them, who play important roles in their respective quests and in the rivalry between the two main characters.
Since I haven't read the novel, it's hard to say for sure. But surely there's the main character who has become the hero's rival. And of course, the hero. There may also be side characters like friends or family of either the rival or the hero who play important roles in the story.
I'm not sure specifically as I haven't read this exact novel. But generally, it might be about a character who somehow becomes a rival to the heroes in the story. Maybe there are conflicts over power, love, or some noble goals.
In this 'I have become the heroes rival novel', the main characters are probably the titular character who has become the rival. They must have some unique traits that set them apart from the heroes. And the heroes, who are likely to have the common heroic qualities like courage, justice - they are the ones against whom the rival is pitted. There might also be some supporting characters who are either on the side of the rival or the heroes, influencing the conflict and the overall story.
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.