Disclaimer: still don't own it.
Also, yes, I'm changing the timeline and events quite a bit.
Xander arrived at the school library just moments after sunset. Giles had called an emergency meeting, no doubt to discuss the events of the morning. When he arrived, he found a scene of moderate chaos. Books were scattered across the tables, and Giles himself was cleaning his glasses, a disgruntled look on his face. Willow was nervously going through a book, while Oz...was Oz. Nothing ever fazed him. He sat, laconically gazing at his red-haired girlfriend. Cordelia, as per usual, was painting her nails while pretending to read, occasionally making snide comments. Buffy, however, was not her usual self. She sat in a chair, pale and shocked. Occasionally, a tear would trickle down her cheek.
Xander snorted. All of this for one dead vampire. They hadn't put in so much effort when he was alive, so to speak, but now that he was dead, they went all out.
"Oh, there you are, Xander." Giles looked up. "Where have you been? We are having a bit of a crisis here. Someone has managed to take out Angelus and most, if not all, of his minions. Obviously, there is a new player in town, someone powerful. With Angelus out of the picture, this town has a power vacuum, one which this newcomer will undoubtedly rush to fill. After all, this is the Hellmouth, a very tempting target for would-be evil lords. We need to research what kind of demon burns its enemies to death and has the power to take out Angelus. Whatever it was, it destroyed the whole mansion. It is too powerful not to worry about."
"Giles! This thing killed Angel! Now I'll never get him back! We have to find it and kill it!" Buffy was on the verge of hysterics.
"Yeah, yeah," Cordelia chimed in. "Send you after something powerful enough to wipe out Angelus and his cronies, when you couldn't or wouldn't take on Angelus by himself. And all for the hope of getting him back? I don't know about you guys, but if I got turned into a vamp, I'd want to get staked. I mean, come on, eternity without mirrors? Please." She went back to idly inspecting her nails.
"You know, Cordy has a point," Xander added. "And just because someone offed Captain Forehead, why would that make them evil? For killing a vampire? We do that all the time, does that make us evil?"
Willow glared at him. "Xander, you're not being very sensitive. Besides, demons kill each other off all the time; that doesn't make them good."
Buffy was looking at them with horror in her eyes. Then, her face darkened as she took a long look at Xander. "You! It was you, wasn't it?! How could you do that? You know I loved him. We could have found a spell, something to bring him back. You didn't have to kill him." She advanced on Xander, hand raised as if to slap him.
As she started to swing, Xander grabbed it. "You, you, you, it's all about you, isn't it?" he hissed. "Well, guess what, Buffy, this wasn't about you. It was about an evil killing machine on the loose in a town filled with sheep. It was about all of those people who've been his victims. Do you even know how many people he's killed here? Do you even care? How many people would he have had to kill before you'd be willing to take action? Who would he have to kill? Me? Willow? Giles? Your mother? She doesn't even know what's out there; she's his perfect victim. He would have had no problem taking her, torturing and turing her, then leaving for you to stake. Yes, I killed him; I wiped out his gang, except for Spike and Dru, who escaped. And the town's a little safer. Word will spread about what happens to vampires here."
By this time, Buffy was in tears. "I'm the Slayer! This was supposed to be my job, my decision! You interfered in my duty! What gives you the right?"
"Your duty? You refused to do your duty when you let him walk away, so I had to do it for you. And let me tell you something. Just because I wasn't chosen to do this, doesn't mean I don't have the right to choose for myself." Xander's face softened. Slayer or not, Buffy was still a teenage girl, and one with a broken heart. "Buffy, I may not have liked the guy, but I didn't want him dead. You shouldn't have to be the one to kill him. I know how hard it is to have to stake someone you love." He looked down. "I had to stake Jessie. I know how much it hurts. You shouldn't have to go through that."
Buffy was crying, and willow had tears in her eyes. Even Cordelia looked sad. They sat quietly for a moment, remembering lost friends.
Giles spoke up. "While I agree that something needed to be done about Angelus, it was very foolish and rash to attempt anything by yourself without telling anyone. If anything had gone wrong, no one would have been able to help you."
Xander blushed and looked down. "I didn't want to worry you, or put you guys in any danger." He looked at Buffy. " I guess this is how you feel when we go out with you, huh?
She nodded and sighed, tears still flowing. "I know you wanted to help, and I know he wasn't my Angel, but it still hurts. It's going to take a while before I can forgive you."
"Take as long as you need; I'll be here for you."
She nodded and turned away. Just then, the library door opened up, and a beautiful black girl walked in.
"Um, can I help you with something?" Giles asked. "It is Saturday night; you do know the library is closed, don't you?" Not realizing the irony of that statement, Giles looked at the girl.
"Excuse me for interruptin' sir," came the reply, "but would you be Mistah Giles?" At his nod, she continued. "I must speak wit' you in private."
Giles shook his head. "You may speak freely here. I have no intention of going off with a perfect stranger at night. Anything you wish to say to me may be said in front of everyone."
"Very well, sir. My name is Kendra, de Vampire Slayer. My Watcher, Mr. Zabuto, sent me here to look into a force of great evil dat was detected here. I was told dat you would be my Watcher while I am here."
"Um, yes, well, you see..." Giles trailed off.
"We already have a slayer," Cordelia said. "Besides, isn't there only supposed to be one at a time? Anyways, the big evil is gone, so you kind of made the trip for nothing."
"What do you mean, you already have a Slayer? I was Called, which means dat the Slayer before me died. How could dere be two?"
All eyes turned to Xander, who shuffled his feet at the sudden attention. "Buffy did die; the Master drowned her, but I did CPR and brought her back to life. There was this whole prophesy thing that said the Master would kill the Slayer but it never said anything about her staying dead. What's the big deal, anyway? Why not have more than one?"
Everyone chuckled at Xander's ability to babble, second only to Willow. Buffy smiled and approached Kendra. "A sister Slayer, huh? I think this could be fun. With you, me and Xander here, the demons don't stand a chance."
Enter Kendra, the Vampire Slayer.