The marks might force them to understand each other better. Since they are soulmates in the context of the fanfiction, they may start to see the reasons behind each other's actions. Harry might begin to understand Voldemort's thirst for power as a result of his own difficult past, and Voldemort might see Harry's determination as something more than just a threat to his plans.
They can also be a source of a strange attraction. Despite their hatred for each other, the marks could create an underlying pull. This could lead to some really interesting character dynamics. For example, in some fanfictions, they might find themselves unable to harm each other directly because of the marks, which would completely change the way their battles play out.
The soulmate marks can create a sense of confusion. Harry, being the hero, might be conflicted about having a connection to Voldemort. It could make him question his own identity and purpose. For Voldemort, it might be a source of irritation or an opportunity to manipulate Harry.
Soulmate marks can speed up the process of relationship building. Since the characters know they are soulmates because of the marks, they might be more open and trusting towards each other from the start. It gives them a sense of security and destiny in their relationship.
In some fanfictions, the soulmate marks might be used to show a hidden connection between them that goes beyond their enmity. It could be a way to explore the concept that they are two sides of the same coin. The marks could also be a source of power for both of them, either by enhancing their existing magic or unlocking new abilities that are only accessible when they are in close proximity to each other.
One interesting concept could be unique designs of the soulmate marks. For example, some fanfictions might have the marks be in the shape of a Hogwarts house crest. Another concept could be how the marks interact with magic. Maybe the marks glow when the soulmates are near each other and can even enhance their magical abilities when they touch. Also, the discovery of the soulmate through the mark can lead to all sorts of adventures and relationship developments in the wizarding world.
The soulmate marks could also cause some initial confusion. Remus, being more reserved, might be hesitant to believe in the marks at first. Sirius, on the other hand, might be more eager to explore. As they deal with their different reactions, they start to communicate more and in the process, their relationship deepens. They might share their hopes and fears related to the marks, and through that, they learn more about each other and fall in love.
In some stories, the tattoos have magical properties that directly influence their relationship. For example, they might cause the two to have shared dreams or feelings. This makes them more empathetic towards each other and helps break down the barriers between them. The tattoos can also be a source of protection for each other in dangerous situations.
In the wizarding community at large, there could be different reactions. Some traditional wizards might not accept a relationship based on a soulmate mark between someone as young as Harry and an older werewolf like Remus. This could lead to them facing discrimination or being ostracized. However, there could also be those who see it as a sign of hope and a new kind of magic. This would then influence how Harry and Remus interact with the wider wizarding world, either having to fight for their relationship or being embraced as a symbol of change.
A very frequent theme is the exploration of destiny. The fanfictions often question if their being soulmates was fated all along. Also, the theme of internal conflict is common. Harry has to grapple with the fact that his soulmate is the most evil wizard, and Voldemort has to face his connection to the 'Boy Who Lived'. It makes for some really intense character development. For example, in some stories, Harry tries to find the good in Voldemort because of their bond, while Voldemort is forced to re - evaluate his hatred for Harry. This leads to a lot of interesting plot twists and turns.
At first, it would be full of conflict. Voldemort is used to hatred and power, and having a soulmate, especially Harry, would be very confusing for him. Harry, on the other hand, would be hesitant but might feel a strange pull towards Voldemort.
Well, it could work in a variety of ways. One possibility is that there is a magical mark that appears on the body when a person meets their soulmate. This mark could have different forms depending on the nature of the bond. Also, the bond might work through shared dreams. The two soulmates might start having dreams where they can interact with each other before they actually meet in person. And the strength of the bond could grow as they spend more time together and get to know each other better. For instance, they might be able to share magical energy or even some of their magical skills as the bond deepens.
One common theme is the idea of a shared destiny. Despite being on opposite sides, they are somehow fated to be connected in this soulmate concept. Another theme is the exploration of the power dynamic. Since Voldemort is so powerful and Harry is the one destined to defeat him, in this fanfiction it could be about how their powers interact on a more intimate level as soulmates.