The theme of forbidden love also often appears. Given their different natures and the context of the original story, their relationship might be seen as something that goes against the norm. Fanfics may delve into how they overcome or struggle with this aspect. Also, the theme of loyalty can be present. Sebastian's loyalty to Ciel in the original is strong, and in fanfics, this loyalty can be further explored in the context of their new relationship dynamic.
I'm not sure about specific fanfics for this pairing, but you can try searching on popular fanfic platforms like Archive of Our Own. There are often a wide variety of works for different pairings in that site.
Love against all odds is also a typical theme. Given their different natures, their relationship might be seen as unconventional or even taboo in the world of the fanfic. So, the story often focuses on how they overcome these obstacles to be together. Additionally, themes of loyalty and betrayal can be found. As they navigate their relationship, they may face situations where loyalty to each other or to their own kind is tested.
There's also 'Alois and Ciel's Hidden World'. This fanfic delves deep into their personalities as an alpha and an omega. It has a great plot that shows how they interact and grow closer over time. The author does an amazing job of portraying their unique dynamic within the story.
One idea could be Sebastian protecting Ciel from other alphas who see Ciel as a desirable omega. Another could be Ciel struggling with his omega instincts while trying to maintain his role as the head of the Phantomhive family. Maybe Sebastian and Ciel could go on a journey together where they have to rely on each other and their bond deepens as a result.
One great alpha x omega fanfic is 'The Omega's New Beginning'. It has an engaging plot where the omega overcomes many challenges. Another is 'Alpha's Redemption' which focuses on the growth of the alpha character in relation to the omega. And 'Bonded by Fate' is also popular, with its unique take on the alpha - omega relationship.
One common theme is the power dynamic. The alpha is often seen as the dominant figure, while the omega is more submissive, and this creates an interesting relationship. Another theme is love against all odds. They might face opposition from their society or families because of their alpha - omega status.
One common theme is the struggle with their different natures. Since Sam is an alpha and Dean is an omega, there's often a push - and - pull dynamic as they try to figure out how to be together. Another theme is protection. Sam usually feels a strong urge to protect Dean.
One common theme is the power dynamic. Usually, the alpha male has more social or physical power, and the fic explores how this affects their relationship with the omega male. Another theme is acceptance. They often have to accept each other's differences, like the alpha accepting the omega's more sensitive nature.