One common theme could be the building of a new relationship, whether it's a friendship or something more. Another might be the exploration of their different personalities and how they interact with each other.
I'm not sure which specific 'chaol meets rowan fanfic' stories are available. You could try searching on popular fanfic websites like Archive of Our Own. There might be various creative interpretations of their meeting in different stories there.
The theme of redemption can also be present. Maybe one of them has a past they're not proud of, and their meeting with the other becomes a turning point in their journey towards redemption. Their interaction during the meeting and afterwards can be a catalyst for positive change. For instance, Rowan might have been a bit of a loner or had a troubled past, but meeting Aelin gives him a new sense of purpose and a chance to be part of something bigger.
Romance is often a common theme. Maybe she falls in love with another character, and the story revolves around their relationship, with all the typical romantic elements like first meetings, misunderstandings, and grand gestures.
One common theme could be the new challenges they face as parents. Raising a baby is no easy feat, and in the fanfic, it might show how they deal with sleepless nights, feeding problems, etc.
In a more action - packed scenario, they might team up to fight a common enemy. Their combined strength and different abilities could make for an exciting battle sequence. Aedion's strategic mind and Rowan's brute force could complement each other well in combat. And after the fight, they could develop a mutual respect that grows into a strong friendship.
Another place could be FanFiction.net. However, the quality and content can vary greatly. You might need to use the search function and type in 'Aedion meets Rowan' specifically to narrow down the results. Some fanfics may be part of a series, so check the related works as well.
Love is a very common theme. Their passionate love for each other is often explored in great detail, from the initial attraction to the deep and abiding love that develops over time.
In 'fellowship meets thranduil fanfic', the theme of mutual understanding is quite common. Since they come from different backgrounds, they need to understand each other's motives and values. Another theme is the struggle against a common enemy. Whether it's the forces of Sauron or some other dark power, they may have to join forces. And the theme of friendship can also emerge, as unexpected bonds may form between the members of the Fellowship and Thranduil's people despite their initial differences.
Overcoming differences is another theme. Cami and Caroline may have different backgrounds or abilities in the original story, and the fanfics might focus on how they deal with these differences to work together or be friends.
In 'archer meets alaya fanfic', a prevalent theme could be the clash of different worlds or ideologies. Archer might come from one kind of background or set of beliefs, and Alaya from another. Their meeting could lead to interesting discussions and conflicts as they try to understand each other. Additionally, themes of redemption or self - discovery could also be present. For example, through their encounter, Archer might learn something about himself that he hadn't known before, or Alaya might find a way to atone for past mistakes.