Okay so I have a few ideas for now
1 Rudolph and Tony meet Rudiger and Anton
2 Rudolph and Tony meet Rudiger and Anton, but Anton had become an vampire
3 Inverse!au
4 Rudolph instead of become friends with Tony, he bite him ( I'm sorry)
5 Tony and Anton are cousins and both have vampire bfs.
6 Your request
Thats all I hope you vote, sorry for bad english
-Hizzi