He can be with other vampire girls, but he wants to be with you no matter what.
The only girl who isn't scared to attack the immortal with the immense ability to change into a bat in an emergency. The majority of girls are jealous of you since you possess the charm and beauty they desire. For men in particular, this makes it easy to divert the immortal.
Sebastian appears impressed by your strategy and desires you could divert his attention in the same way you did with the immortal.
He will almost always show up out of the blue to talk to you, but you're not interested because you're into blood-hunting rather than in a relationship. which irritates him a little.
Your parents are throwing a big party one day. Everyone is invited, even him. He looks around, trying to find you. He then hears a pair of high heels descend the grand staircase.
His eyes enlarge when he sees you wearing this gorgeous deep red gown with a plunging neckline, elaborate ruching, floral waist embellishments, a flowing cape, and a dramatic high-slit design that radiates power and elegance. "Oh my blood," he says in a low voice.