I don't have knowledge of Adam Ariel Schrag's vampire novels. However, in most vampire novels, there is often a sense of the otherworldly. There could be a love - hate relationship between vampires and humans in his works. Also, there might be some unique vampire powers and weaknesses that are distinctively portrayed.
I'm not specifically familiar with Adam Ariel Schrag's vampire novels. However, some popular vampire novels in general are 'Dracula' by Bram Stoker and 'Interview with the Vampire' by Anne Rice. Maybe Schrag's works have their own unique take on the vampire genre.
One common theme is the struggle between humanity and vampirism. Adam often has to deal with his vampire nature that craves blood while still having some human emotions left. For example, he might feel guilty after feeding on a human.
Ariel could be a character who is often in a state of distress or fear in horror novels. Maybe she is a victim of a supernatural force or a serial killer. For example, she could be a young girl living in a haunted house, constantly hearing strange noises and seeing apparitions.
Adam could be developed by exploring his origin story more deeply. Maybe he has some special abilities that are unique to him. These abilities could be related to his family heritage or something that happened to him in his past. As he discovers more about these abilities in the context of the 'Abraham Lincoln Vampire Hunter' world, he grows as a character. He could start out as a bit of a loner, but as he teams up with others, he learns the value of teamwork and friendship.
There's also 'Adam, the Vampire Prince'. In this fanfiction, Adam is a prince in the vampire world. It delves into the politics and power struggles within the vampire society, with Adam at the center. The descriptions of the vampire court and its traditions are quite fascinating.
I'm not sure who Ariel is in this context without more information. It could be a unique character created specifically for this 'never - ending story' that has its own set of characteristics and a role within the plot.
Ariel could be any character created by the fanfic author. It might be a mermaid, as the name Ariel is often associated with mermaids in popular culture.
Some popular ones might include those with unique fantasy settings, like 'Ariel's Enchanted Quest'. It often features a young protagonist named Ariel who embarks on an exciting adventure filled with magic and mystery.