@TVDloveanddevotee I'm not sure on how to continue your story's, the best advice I could give you on that is; Listen to music and just write random things then read through what you've got and see if you like it.
As for some ideas for new books, why not try write a story were Jeremy Gilbert has a twin sister who's mated to; The Mikaelson family, Stefan, Caroline and Bonnie. In this story Elena be more like the ''mother figure." Or something another than portrayed as " the attention seeker." like in some Fan Fictions I've read.
Maybe in this story the OC could be running from her past or maybe she's could be running from her future. That's all I could come up with.
I hope this helps you find inspiration. Have an amazing day.