One common theme is the struggle between the vampire's natural blood hunger and their desire to coexist with humans. They often have to fight their instincts to feed on people they may care about.
Another theme is the search for a cure or control over the blood hunger. In many fanfictions, vampires are constantly looking for ways to suppress their thirst, whether it's through magic, science, or self - discipline. Also, the theme of the vampire's identity being tied to their blood hunger is quite common. How they view themselves in relation to their insatiable thirst.
There's a fanfiction called 'Bloodthirsty Nights'. In this story, the vampire protagonist has an insatiable hunger for blood that gets him into all sorts of trouble. It's really interesting to see how he tries to deal with it. Also, 'Hungry for More' is a good one. It shows a different take on vampire blood hunger, with the vampires having to face the consequences of their actions due to their unquenchable thirst.
Love is a very common theme. Given the vampire - human interactions in both 'Blood Ties' and 'Vampire Knight', fanfictions often explore romantic relationships between these two groups. It could be a forbidden love or a love that overcomes the differences between species.
Love and sacrifice are common themes. The blood sharing is often seen as a way for Damon or Elena to show their love and willingness to protect each other. It's a very intimate act in the vampire world, so it symbolizes a deep connection.
One common theme is immortality. Vampire blood often holds the key to their eternal life, and sometimes humans who consume it might gain a form of extended lifespan or special powers. Another theme could be power. In many vampire novels, the older and more powerful vampires have a stronger, more potent blood. It can also be related to the concept of seduction. The act of drinking blood is often described in a sensuous way, symbolizing the vampire's allure over their victims.
One common theme is identity. Harry has to figure out who he is now that he's a vampire. Another is the idea of power. Vampirism often brings new powers, and Harry has to learn to control them. And of course, there's always the theme of relationships, how his new state affects his bonds with others.
One common theme is the eternal struggle between vampires and werewolves. Since they are often bound by blood in some way, this can fuel their hatred or attraction. Another theme is the idea of forbidden love. Given their different natures, a relationship between a vampire and a werewolf is usually seen as taboo, yet the blood connection can draw them together.
Love is a very common theme. Often it's a forbidden love between a human and a vampire, like in many classic vampire stories. The two beings from different worlds are drawn to each other, but their relationship is fraught with difficulties due to the vampire's nature.
One common theme is friendship. Gabi and Cooper are often shown supporting each other in their pursuits, whether it's related to food or personal growth.
One common theme is the exploration of new or hidden magic. Characters often seek power through discovering magic that was previously unknown or forgotten in the wizarding world. For example, they might find ancient spells or artifacts that give them extraordinary power.
One common theme is the expansion of character backstories. Writers often dig deeper into a character's past, like where they came from before they knew they were demigods. Another theme is alternative romances. Since there are many characters in the 'Blood of Olympus' world, fanfiction writers like to pair them up in different ways than in the original.