Well, adventure is a big theme. The harem often accompanies Spike on various adventures, and they face challenges together. Also, there's the theme of loyalty. The members of the harem are usually loyal to Spike, and he in turn is loyal to them in different ways. For instance, in some fics, when Spike is in danger, the harem members will do anything to protect him. This shows the loyalty that binds them together.
One common theme is friendship. Despite the harem aspect, Spike often forms deep friendships with the characters in the harem. Another is growth. Spike usually grows as a person through his interactions with the harem members.
The theme of acceptance is quite common. Spike has to accept the fact that he has a harem and the responsibilities that come with it. And the harem members have to accept each other as well. Another theme could be adventure. Spike and his harem often go on adventures together, facing new challenges and exploring new places. This adds an element of excitement to the fanfiction.
One common theme is the contrast between their personalities. Spike is often shown as energetic and a bit impulsive, while Maud is very calm and matter - of - fact. Their differences create an interesting dynamic in the stories.
One common theme is unrequited love. Often, Spike has strong feelings for Rarity while she may be initially oblivious or focused on other things. Another theme is growth. Their relationship helps both of them grow as characters, like Spike becoming more confident and Rarity learning to see beyond appearances.
One common theme is the exploration of their unlikely relationship. Given their different personalities and backgrounds in the original source material, fanfics often delve into how they might come together. Another theme is power dynamics, as Spike has his vampire nature and Willow has her growing magical powers.
Friendship is a common theme. Spike and Applebloom can start as friends and gradually develop deeper feelings. Another theme could be adventure. They might go on an adventure together in Equestria and their relationship evolves during that journey.
One common theme could be friendship among the characters in the harem. Another might be Spike's growth and development as he interacts with multiple characters in an anthro - style setting.
Another theme might be mentorship. Shining Armor could be seen as a mentor to Spike, guiding him in different aspects like magic or life skills. And also, adventure is a possible theme. They might go on adventures together, facing different foes and obstacles.
Often, in 'angel x spike yaoi fanfic', themes of redemption and self - discovery can be found. Since both characters have their own dark pasts, the fanfics might explore how their relationship helps them to come to terms with their pasts and grow as individuals. Also, themes of forbidden love are quite common as their relationship in the original context might not be so straightforwardly romantic, and yaoi takes it in a male - male romantic direction which can be seen as 'forbidden' in the original setting.
One common theme is friendship. Since they are from different species, their friendship development is often a central focus. For example, they might start off as strangers but gradually become close friends through shared experiences.
One common theme is friendship evolving into something more. Spike and the reader often start as friends and then develop deeper feelings. Another theme is self - discovery. As the relationship progresses, both characters learn more about themselves.