Half-Blood Master and Half-Blood Servant

Rin didn't meet any demons in her young life unlike Yukio. Instead, she met a Vampire who took her on a whim as a pupil while juggling school and the monastery NONE THE WISER(their fault for leaving her often alone). Rin grew up a magus and on her fifteenth birthday got slapped Command Spells and is now en route to Romania. If only Kairi Shishigou knew what he had to deal with...