Most of the time, the hero/heroine is initially repelled by the villain's actions or nature. But then, the villain may show a different side, perhaps a more gentle or understanding side in private. This creates a sort of internal struggle for the hero/heroine. In 'Poison Study' by Maria V. Snyder, Valek is a rather intimidating and morally ambiguous character. Yelena has to work with him and over time, she discovers his loyalty and other positive traits, and their relationship evolves into a romantic one as she peels back the layers of his 'villainous' exterior.
Often, at first there is a lot of animosity. The heroine is understandably angry and scared due to being kidnapped. But as the hero shows some kindness or vulnerability, the heroine begins to see him in a different light. For example, he might protect her from other threats while she is in captivity.
Often, it starts with a professional relationship. The nanny is hired to take care of the kids or do household work. As she spends time in the house, she and the male lead start to notice each other. Small interactions, like sharing a meal or talking about the kids, lead to a growing interest.
Often, super villain origin stories develop from a sense of injustice or being wronged. They might start as normal people who experience something that shatters their view of the world. For example, if a person is betrayed by someone they trusted deeply, like a friend or a family member, it can lead to a downward spiral into villainy.
In 'obsessed hero romance novels', the hero often has an intense focus on the heroine. He might be constantly thinking about her, like in 'Twilight' where Edward is always aware of Bella's whereabouts and her safety. His actions are mainly centered around her.
In kidnapped romance novels, often the initial encounter of kidnapping creates a sense of forced proximity. This forced closeness makes the characters really get to know each other on a very personal level. For example, they might start by hating each other, but as they share their stories and experiences while in the captivity situation, they begin to understand each other's motives and fears. Then, small acts of kindness or protection within that captive environment can start to kindle the romantic feelings.
Typically, they start with a lot of conflict. For example, they might be rivals at work or have some sort of long - standing feud. Then, something forces them into close proximity, like a shared project or a situation where they have to live together. This proximity leads to an unexpected physical attraction. They start with this 'benefits' part while still being enemies on an emotional level. As time goes on, they gradually start to understand each other better, and the emotional walls start to come down, eventually leading to a deeper, more loving relationship.
Often, in betrothed romance novels, the relationship starts with an obligation or a family - arranged betrothal. Then, the characters start to discover each other's true selves. For example, they might start with small conversations during formal events. As time passes, they might share secrets or have small adventures together, gradually falling in love.
Typically, the marriage contract is like a starting point. It forces the characters to be in close proximity. For example, they might have to live together or attend social events as a couple. This leads to them getting to know each other better.
Often, they start with some sort of initial dislike or misunderstanding. For example, in many novels, the roommates might have different lifestyles or personalities that clash at first.
In wounded hero romance novels, the hero's character development is a complex process. His wounds can be physical, emotional, or both. These wounds act as barriers to his relationship with the heroine. To develop his character, the author might show how he overcomes his insecurities bit by bit. He may start to change his behavior as he falls in love, gradually letting go of his past pain. For instance, in a story where the hero has been betrayed in the past, he might initially be very guarded around the heroine. But as the story unfolds, he realizes she is different and begins to trust again, which is a big part of his character development.