Love and loyalty are very common themes. Their relationship is often depicted as one of deep love and unwavering loyalty. They are committed to each other through thick and thin.
One common trope is the 'love - at - first - sight' or 'instant attraction' trope. Given their characters' charm and good looks, it's often depicted that they have an immediate connection when they first meet. Another is the 'damsel in distress' trope where Cordelia might be in some sort of trouble and Chrom comes to her rescue, which then deepens their relationship.
Love and loyalty are common themes. Cordelia's unwavering loyalty to Chrom is often explored, and how that loyalty turns into romantic love. Another theme is sacrifice. In the context of the game's world, they might be in situations where they have to sacrifice for each other or for their kingdom.
A common characteristic is the exploration of their different social standings. Chrom being a prince or leader, and Cordelia a skilled pegasus knight. Fanfictions might play with how they bridge that gap in their relationship. For example, some might show how they support each other in their respective roles. Another aspect could be the setting. Since they are from a fantasy - like world, fanfictions may expand on the lore of that world and how it impacts their relationship.
One great 'cordelia x chrom fanfic' could be 'A Bond Beyond Kingdoms'. It beautifully portrays their relationship, showing how they support each other in times of war and peace. The story focuses on their emotional connection and the challenges they face together as leaders.
Love and sacrifice are common themes. Given their story in the game, their relationship can be explored in terms of how far they would go for each other.
It's hard to say without actually reading a lot of them. But it could be themes like friendship, if they are characters that can form an interesting bond. Maybe adventure if their story takes place in a world full of action.
One great place to start looking for Cordelia x Chrom fanfiction is on Archive of Our Own (AO3). There are numerous stories there with different themes and plotlines. Some might focus on their relationship development during the events of the game they are from, exploring how they first met and the growing feelings between them. Another option could be to check out fanfiction.net, though the collection there might be a bit more scattered in terms of quality and organization compared to AO3.
Love and friendship are common themes. Their relationship often starts as comradeship and evolves into love. Another theme is loyalty, as they are loyal to each other and their cause. Destiny also plays a role, as in many fics they are seen as destined to be together.
Another common theme is sacrifice. Many fanfics show either Chrom or Sumia being willing to sacrifice for the other. For example, one might be ready to put themselves in danger to save the other from harm. This shows the strength of their bond. Also, themes of leadership and support often come up. Chrom as a leader and Sumia as his partner, how she supports him in his leadership role and how he in turn supports her personal growth.
One common theme is the exploration of their unspoken feelings. In the show, their relationship was complex, and fanfiction often delves deeper into those emotions that were hinted at but not fully explored. For example, how they might deal with jealousy when one of them is interested in someone else.