backstory:
You are Y/n Mikaelson and you are Niklaus Mikaelson's twin sister. You and Klaus were born to the original witch and a werewolf. When your mom turned your family (the original family) into vampires you and Klaus became the original hybrids. Mikael (your half siblings father) hated you and your twin because you weren't biologically his children. You started calling your twin "Nik" as a nickname because it was your way of calling for him or talking to him while everyone else called him Klaus or referring to him as his full name.