She likes her and she finds vampires comforting, since she can assume they are as old as they look to her -- one of the perils of being longlived is that Tazendra isn't quite sure how to treat normal humans, since most of them are the age of small children in her opinion. So it's 'you can't possibly have the experience you pretend to have' (except when they do).

Plus, you know, Tazendra generally likes people.