Their relationship can be developed through shared experiences. For instance, when they fight side by side against a common enemy. This would create a bond of trust and mutual respect between them.
The relationship could be developed through moments of vulnerability. Maybe the Tarnished gets injured and Sellen has to take care of him. Or vice versa. These moments of relying on each other can make their relationship more profound. Also, they could have disagreements at first, but as they work through them, they learn more about each other and their relationship grows stronger.
A more complex plot could involve a prophecy that only the Tarnished and Sellen together can fulfill. However, there are forces at work trying to prevent them from doing so. They must overcome political intrigue, betrayal from within their own ranks, and the ever - present danger of the Lands Between's many terrors. Their love story could develop as they fight against all odds to fulfill the prophecy.
Perhaps a near - death experience where Odd saves Aelita or vice versa. This would create a strong emotional connection between them. After that, they would be more protective of each other and their relationship would grow into a more intimate friendship or even something more romantic over time.
To develop their relationship, you could show them in normal, everyday situations. Like them having coffee together and just talking about their dreams and fears. This would humanize them and make their relationship more relatable. Also, having them save each other's lives in different scenarios would strengthen their bond. Maybe Spiderman saves Gwen from a falling building one time, and then Gwen saves him from a dangerous chemical spill another time. And then there could be moments of jealousy when another character shows interest in either of them, which would make them realize their true feelings for each other.
Their relationship can be developed by having them train together. Naruto can share his experiences and wisdom gained from his own training and battles. Konohamaru can then look up to Naruto even more and try to implement those teachings in his own ninja way.
Their relationship can be developed through shared adventures. For example, going on quests where they rely on each other's skills. Rex might need Mythra's combat abilities and Mythra could need Rex's determination and kindness.
To develop their relationship, you could explore their past. Maybe there were times when they first fused into Garnet and had doubts about each other. By delving into these memories and how they overcame them, it can strengthen their relationship in the fanfic. Also, having them face new challenges together, like dealing with a new type of gem enemy, and seeing how they support each other through it.
Their relationship can be developed through shared experiences. For instance, if they get caught in a rainstorm together and have to find shelter. During this time, they start talking and realize they have more in common than they thought. It could also be developed through competition. They enter a local contest, and at first, they are rivals but then they see how the other person is also trying hard and start to respect each other.
Their relationship can be developed through shared experiences. For example, when they encounter a difficult Pokémon battle together, Pikachu can protect Lillie, and Lillie can in turn use her skills to support Pikachu. This mutual reliance will strengthen their bond.
Their relationship could start with a shared goal, like protecting a particular person or place. Through working together towards this goal, they get to know each other better.
In a 'human x slime girl' fanfic, the relationship can start with curiosity. The human might be intrigued by the slime girl's appearance or abilities, and the slime girl could be interested in human culture. As they spend more time together, they start to care for each other. They could also have moments of vulnerability, like when the slime girl is in a difficult situation where her slime - like nature is a disadvantage, and the human helps her. This would strengthen their bond. Moreover, small acts of kindness, like the human sharing food with the slime girl (even if she has a different way of 'eating'), can be a step in developing their relationship.