Blaise appears first in Secret Vampire where we learn that she is, along with Thea, one of Ash Redfern’s witch cousins, and that, unlike Thea, Blaise finds a certain amusement in messing with people. This is expanded upon in Spellbinder where Blaise must compete with her cousin for a human boy, Eric Ross.
Blaise has grown up with her cousin Thea since both of their parents died when the girls were young. In Spellbinder they’ve just gotten expelled yet again due to Blaises antics. It seems that Blaise enjoys playing with the minds of human boys. Her last toy was named Randy Marik. It seems that Randy “burned the school down for her.” Indeed, we see Blaise manipulating humans at every turn, especially guys. She makes one guy act like a dog and gets another to give her his parents car. The only boy that she can’t seem to get is Eric, and this bothers Blaise. She’s competitive, and stubborn, and she does whatever she can to achieve the result she wants. She has the brain to go with the powers too. As Thea says “Despite her frivolous act, she wasn’t stupid.” Blaises behavior is excused by her cousin in the story when Thea says things like “What Blaise does—it’s just her nature, the way it’s a cats nature to play with mice.” Blaise does change though, a little, learning to see things from other points of view, mainly because bond with Thea is extremely important. Although Blaise see’s humans as vermin, she’s the one who helps Thea to get away with Eric in the end. And when Thea asks her not to hurt any more humans Blaise “sighed noncommittally” which may not be seen as a big change, but it’s more encouraging than an outright objection.
Spellbinder by L.J. Smith