The OC could be a shy and artistic girl. She loves to draw and often sketches the beautiful landscapes around Rudolph's castle. Her long hair and big eyes give her an innocent look. She wears simple dresses and always has a sketchbook with her.
Maybe the OC has a special power or ability that Rudolph needs. For example, the OC can sense when danger is near. They team up to protect Rudolph's vampire family from a group of hunters who have come to town. As they work together, a deeper bond forms between them.
Friendship is a very common theme. Since Tony and Rudolph are the main characters in this fanfiction concept, their bond and how they support each other through different situations is often explored.
They could be best friends. Tony might be the first human to accept Rudolph for who he is, and Rudolph might see Tony as someone he can trust completely.
There could also be a character like a wise old vampire in the community who acts as a mentor to Rudolph, guiding him through the difficulties of being a young vampire in a world that has both vampire and human elements.
One place to start looking for such fanfiction could be popular fanfiction websites like Archive of Our Own. Just search for 'the little vampire tony x rudolph' on there, and you're likely to find some interesting reads.
Perhaps Rudolph discovers a hidden power within himself that helps him protect his vampire family from a new threat in their town. This could involve a series of challenges where he has to learn to control this power.
Well, it could be about Rudolph and Tony going on an adventure together. Maybe they explore a spooky old castle that has some hidden secrets. They might encounter other supernatural beings and have to work together to overcome challenges.
Rudolph is often cautious and thoughtful, while Tony is more impulsive and bold. Tony's boldness can encourage Rudolph to take risks he might not otherwise take, and Rudolph's caution can keep Tony from getting into too much trouble.
Obviously, Rudolph is one of the main characters as the little vampire whose love story is the focus. There may also be the character he falls in love with, perhaps a human or another supernatural being. And probably his vampire family members could be important characters too, as they might influence his relationship or present obstacles to his love.