Since Felli is somewhat in dispute,
and I realized I totally forgot about manga entirely, I've got a better one. One that actually rivals, and may very well defeat Rika in the long run.
Misaki Minato from
Blood Alone
Loli vampire with a very strong yet healthy attachment to her servant/protector. While this is fairly common in loli-vampire stories, Misaki stands out because she is, largely, very much a regular girl. She wasn't turned that long ago, so most of the more ruthless aspects of her vampirism lay dormant (a stark contrast to series like Vampire Bund). She gets
very jealous of women who attempt to flirt with her protector, and it is particularly amusing because if she actually aged, she would be right around them in physical age. There is an innocence and maturity that she goes between, and it is very much genuine, unlike so many characters similar to her. She might be stuck in a loli body, but she is a young woman for certain.