Another theme might be the discovery of each other's true selves. As the story progresses in the fanfiction, yuma and dextra could gradually learn more about each other on a deeper level, which deepens their love. This can involve revelations about their pasts, their dreams, and their insecurities.
The theme of sacrifice also often appears. In some fanfictions, either yuma or dextra may have to sacrifice something they hold dear, like a personal ambition or a relationship with another character, in order to be with the one they love. This adds drama and depth to their love story.
I'm sorry I can't recommend specific yuma and dextra love fanfiction directly. But you can try to search on some well - known fanfiction platforms like Archive of Our Own (AO3). There are a large number of fanfictions about different topics and characters, and you might be able to find some interesting ones about yuma and dextra there.
Overcoming challenges together is also a popular theme. This could include battling against villains in the Yu - Gi - Oh! universe while also dealing with their own relationship issues. It makes for an exciting and emotional read.
One common theme is friendship. Yuma and Tori are often depicted as having a strong friendship that endures through various challenges in the stories.
Another theme could be rivalry. There are fanfictions that play up the competitive side of their relationship. Maybe they compete in a new type of dueling tournament or battle for a rare card. This adds an exciting element to the stories.
A common theme is the power of friendship. Since they are partners in the dueling world, many fanfictions explore how their friendship develops and overcomes obstacles. For example, they might face a misunderstanding that threatens to break their bond, but they work through it.
One common theme is friendship. They often support each other through tough times in fanfictions.
One common theme is self - discovery. When Yuma travels through time, he often learns more about himself. Another theme is the impact of small actions. In many of these fanfictions, Yuma's actions in the past or future can have a huge effect on his present. For example, in some stories, a small change he makes in the past can completely change the course of his life in the present.
One common theme is growth. Yuma and Yui might grow as individuals while being in a relationship. For instance, they could learn to be more confident or more understanding. Also, family can be a theme. Maybe their families have an impact on their relationship, either supporting or opposing it. In some fanfictions, there could be a theme of mystery, like there's a secret about one of them that the other has to uncover as their relationship progresses.
One common theme could be friendship evolving into something more. Given their relationship in the original context, many fanfictions might explore how their bond deepens over time.
As I don't have much knowledge about this particular fanfiction, we can only speculate. If the 'neck' is a key element, it might be related to themes of vulnerability. A kiss on the neck can be seen as an intimate act, so perhaps themes of trust and intimacy are common. It could also be that the story is set in a world where such an action has special significance, like in a supernatural or fantasy setting. In that case, themes could include magic, power dynamics, and the consequences of such an intimate act within that fictional world.