One common theme could be forbidden love. Since lemon fanfictions often involve more mature or passionate relationships, a forbidden aspect can add an extra layer of intrigue.
In Alexander and Raven lemon fanfiction, the theme of redemption can sometimes be present. Perhaps one of them has a past they are trying to overcome, and their relationship becomes a part of that journey. Also, the theme of secrecy often pops up. Keeping their relationship a secret from others can create a lot of tension and drama in the story. Additionally, exploration of new emotions and experiences related to their relationship is a common thread that runs through many such fanfictions.
One common theme is probably the anticipation and fear of the new life. Both Raven and Alexander may be worried about how their lives will change. Another theme could be the support system around them, like their friends and family's reactions to the pregnancy.
Love is a very common theme. Their unique, somewhat forbidden love as a human and a vampire is often explored. It shows how they overcome differences to be together.
Love and conflict are often common themes. Their relationship might be filled with love but also face various conflicts, either from external forces or their own internal struggles.
Since 'lemon' often refers to mature content, it's not appropriate to discuss common themes in that context. But in general Raven and Starfire fanfictions may have themes like friendship, loyalty, and the contrast between their personalities.
Common themes in Naruto and Raven lemon fanfiction may include power dynamics. Since Naruto has his own set of powers and abilities in the ninja world and Raven has her powers, there could be a theme of who is more dominant in the relationship, both in terms of power and personality. Another theme could be the cultural differences between their respective worlds. Naruto's world has its own set of values, traditions, and taboos, and Raven's world also has its own. How these interact and are navigated within the context of their relationship can be an interesting theme. Also, the theme of transformation is often present, as both characters may change and grow as a result of their relationship.
One common theme could be the exploration of the relationship between Harry and Raven. It might focus on their emotional connection and how it develops. Another theme could be the challenges they face together, perhaps from the outside world or within their own relationship.
One common theme could be friendship evolving into something more. Since they are often friends in the original context, fanfiction might explore a romantic shift.
I'm not sure specifically which 'Alexander and Raven' you're referring to. There could be a lot of different fanfictions out there. You might try searching on popular fanfiction websites like Archive of Our Own. They usually have a wide variety of works and good search functions to help you find relevant stories.
One common theme could be exploration of Raven's character. Since she has a complex personality in RWBY, fanfics might delve deeper into her backstory, her relationships, and her motives.
One common theme could be the relationship between Robin and Raven. It might explore their emotional connection in a more intense way compared to the original source. Another theme could be their individual growth within the context of the fan - created scenarios.