One common theme could be adventure. Since both Hiccup and Merida are known for their adventurous spirits in their respective movies. They might go on quests together in the fanfiction.
Fem Hiccup's more introverted nature might be a contrast to Male Merida's extroverted and brash personality. Hiccup might be hesitant to engage in some of Merida's wilder adventures at first. However, Merida's enthusiasm could draw Hiccup out of her shell. And Hiccup's calmness in the face of danger could help Merida learn to control his impulses a bit better. They would have an interesting dynamic where they learn from each other's strengths and weaknesses.
Another option is to check out Tumblr. There are often fanfiction communities and blogs dedicated to sharing and discussing different fanfictions. You might be able to find some Fem Hiccup x Male Merida fanfictions there, or at least get some leads from the community.
One possible plotline could be that Fem Hiccup and Male Merida meet in a forest while on their respective adventures. They initially clash due to their different ways of doing things. Hiccup is more methodical and Merida is more impulsive. But as they face a common enemy, like a giant magical beast, they learn to work together. Hiccup uses her engineering skills to create traps and Merida uses his archery skills to lead the beast into the traps. In the end, they become good friends and respect each other's cultures and abilities.
Another fanfiction could start with Merida getting lost in the Viking lands. Hiccup finds her and at first, they have a bit of a misunderstanding because of their different cultures. But as they spend time together, Hiccup helps Merida understand the ways of the Vikings and Merida teaches Hiccup some of her own skills, like how to better track in the forest. Eventually, they become good friends and help each other out in various adventures in the Viking world.
Adventure is also a big theme. Since both characters are known for their adventurous spirits in their respective movies. Fanfictions often involve them going on quests or facing challenges together, which strengthens their bond and love for each other. For example, they might team up to fight a common enemy or explore a new, mysterious land.
First, you need to understand the characters well. Hiccup is known for his intelligence and ability to connect with dragons, while Merida is strong - willed and an excellent archer. Incorporate these traits into their interactions. For example, Hiccup could use his knowledge to help Merida in a situation, and she could show her courage in return. When it comes to the kiss, build up the tension gradually. Don't rush it.
Well, it could be a story where Hiccup and Merida are from different kingdoms or tribes. They meet by chance, perhaps during a diplomatic event. Their initial interactions are filled with misunderstandings because of their different cultures. But as they get to know each other better, they start to see the good in one another. And then, the kiss could be a moment of realization of their deepening feelings, a moment that bridges the gap between their two worlds.
They might start off as rivals. Merida is used to being independent and in charge, and Hiccup has his own leadership style with the dragons. But as they get to know each other, they realize they can work together. For instance, they could go on a quest to find a magical item that is said to bring peace to both their lands.
Well, in a Merida meets Hiccup fanfiction, it could start with Merida getting lost in the land where Hiccup lives. Hiccup finds her and is intrigued by her boldness. They start sharing their stories. Merida talks about her adventures in her kingdom and Hiccup tells her about his life with the dragons. As they spend more time together, they learn from each other's ways of life and grow as individuals.