I don't own BTVS or Avengers. Sorry for bad grammar. The time line is twisted. I'll try to make it funny.
It was a late night. Fury was walking home from a grocery shop (even he needs to go shopping). He was walking in a dark street, some of the streetlamps were glowing, but some didn't. He was hardly seen in the dark (mostly because of his dark clothes, dark skin and eye patch).
*I have the feeling that I'm being followed. Better run him in a trap so I can see who that bastard is.*
Fury went into a dark alley with a dead end. He put his grocery bags on the ground, pulled out his gun and waited.
"Why the hell are you following me?" Fury said felling that person's presence. He turned around and saw a woman with a creepy smile.
She just kept on smiling like a creep. Then all off a sudden the woman's face turned like a monsters face. Fury instantly started to shoot that monster, but it was no use. The monster started to slowly walk into Fury's direction. Fury knew he didn't have a chance against an immortal monster so he used a smoke bomb and retreated.
Fury was home breathing heavily. After he got his breading to normal he locked his door and windows. He wanted to be sure that the monster wouldn't get in his apartment and attack him once more. Then he started to prepare his late dinner, because no immortal monster would stop him from making his dinner and eating it while cleaning his guns.
Next day!
Fury had brought all the Avengers to discuss his attacker. Before that he made a photo robot of the attacker to show The Avengers how these monsters look.
"Does someone of you know what she is?" Fury asked after telling them what happened in the alley.
"Not she but they? I just dug up some similar attack cases. They say that the victims are found with two holes in their neck and they have no blood left. It's like the attacker drained their blood." Tony said while reading the cases.
"Sounds like vampires." Barton said joking.
"Don't be like a child who is frightened by Halloween stories." Natasha said annoyed.
"No he's right. Those are vampires. In my home those are legends, but by your image I can tell that it's true." Said Thor thinking how the legend goes.
"So how do we kill them?" Steve asked curious.
"The legend doesn't say that. But it talks about a chosen one. In every generation there is a chosen one… She alone will stand against the vampires, the demons and forces of darkness. She is the slayer." Thor said it acting his teacher's voice while he was saying that.
"So how do we find the slayer? If she exists." Steve was trying to imagine how she would look.
"Tony look in the cases and find a name that is mentioned most often." Bruce commanded Tony. Everyone was looking at Tony waiting for him to say something.
"Your staring won't help me work….. The most mentioned name is Buffy Summers. It says she burned down a gym in her school. Then vent to live in Sunnydale." Tony was kind of interested in the part where she burned the gym down.
"I'll send some agents to bring her to us." Said Fury storming off.
"So how do you think the slayer will look? Muscles and scars?" Barton asked.
"You can't be serious by that." Natasha stud up and went to do her stuff.