Karen is pretty sure it's gonna be a good year. She already has friends, she's no longer consumed by grief at the death of her parents, she has all her classes picked out, and she's going up against the forces of darkness armed with knowledge of her destiny and supported by, like, three ancient mentors who actively want her to succeed and not just her sister and a random vampire who is now one of her best friends. She has a really good first two days of school, and at the end of them she is more sure than ever that this is gonna be a really, really good year.
On the third day of school, a guy in some kind of suit jacket stops her on her way in.
"Hi!" she says, brightly. "Can I help you?"
"Yes, I believe you can. You're Karen Teller?"
"Yep. That's me."
"Wesley Wyndam-Pryce. Now, Karen, what I'm about to tell you may shock and confuse you, but I would like you to hear me out. I know you may feel that this is unnecessary, but - "
"Sure! I do sort of need you to hurry it up, I gotta get to first period, but yeah, down to be shocked and confused."
The man takes a deep breath. "You, Karen Teller, are a vampire slayer. You are the world's first and often final line of defense against not only vampires, but against a whole host of supernatural evils. I expect this to be hard for you to accept, but I've come prepared to show you evidence, both of the demons you must fight, and of your own nature, but you, Karen Teller, must accept your destiny and protect this world."
"Yep. Already on it."
"How did you come to know about this?"
"I figured it out."
Wesley takes a moment to look deeply confused and a little disappointed, then sighs. "Well. Very good then. As I told you, my name is Wesley Wyndam-Pryce. I have been assigned to work as your watcher, to train you in the art of slaying and to deploy you against the forces of evil that are at work in this town. You'll no longer have to fight this war without support."
"Oh," says Karen. "...OK."
"Yes! Well then. I think we should start immediately."
".....OK. But I do have to get to first period."
"Right! Right, yes, of course. It shouldn't be necessary to immediately interrupt your education. We shall start immediately after classes."
"Oh. OK. I'll - see you," she says, lamely, and walks off to class before she has to say anything else.
Paging Alex. Heads up. Watcher's council's found us.