The theme of overcoming differences is quite prevalent. Maybe Emily comes from a different social class or has different powers/abilities than Ulric. But they have to work together and in the process, they overcome these differences. Additionally, the theme of loyalty is often seen. They are loyal to each other no matter what challenges they face, whether it's a threat from an external enemy or internal doubts within their relationship.
You can start by looking on fanfiction websites like Archive of Our Own. It has a vast collection of different fanfictions, and there's a good chance you'll find some about Ulric and Emily there.
There could be ones focused on their daily lives. Maybe they are students in a magical school and their interactions during classes, study sessions, and school events form the basis of the fanfiction. It shows how they get to know each other better over time.
There are many platforms where you can find emily x ulric fanfiction, such as Archive of Our Own (AO3). Just search for 'emily x ulric' on it, and you'll get a list of relevant stories. Some might be about their adventures together in a fictional world, while others could focus on their relationship development.
There could be a wide variety of Glitter Force Emily x Ulric fanfictions out there. Some might focus on their adventures together within the Glitter Force world. Others could be more about the development of their relationship, like how they first met and gradually grew closer. However, without actually searching on the relevant platforms, it's hard to point out particular ones.
One common theme is adventure. Nyx is often depicted going on quests or missions with the reader. Another is romance, of course, showing the growth of their feelings for each other.
One frequent theme is the struggle between two different worlds. Emily represents a more normal world, while the Outsider is from a much more mysterious and often dangerous realm. Their relationship in the fanfiction often explores how they bridge this gap. Also, trust is a big theme. Emily has to decide whether she can trust this strange Outsider, and the Outsider has to trust Emily not to expose his secrets. There can be a lot of internal conflict for both characters as they navigate this new relationship.
Another good one is 'In the Shadows with You'. It's a bit more action - packed. The plot involves the two of them working together to solve a complex case while also dealing with their growing feelings. The way the author writes the chemistry between Emily and the reader is really intense and makes for an exciting read.