Narnia/Angel crossover. Spoilers for the Last Battle and Season 5.
Disclaimer: No copyright infringement is intended.
Charles thrust his sword into the heart of a slimy-looking demon, turning to slice off a vampire's head with a grunt of pain. Fatigue had set in, his gut wound throbbed, and his limbs now seemed to be moving on their own. He kept an eye on Angel, Illyria, Connor, and Spike, stepping in to backstab a demon Spike hadn't noticed. They didn't speak, only communicated when they had to with nods and grunts. Backed against the side of a tall building, the five of them fought desperately next to a heap of dead demons and giants. A smaller pile of weapons they had collected was shared among them as needed. Charles reached for a bow and arrows to aim at a particularly vicious-looking vampire when he realized someone else was already using them. He had to look twice when he realized it was a very ordinary-looking, elderly woman. She was dressed like a wealthy society lady, with a fur coat and a string of pearls, and her dark hair with a few streaks of grey was done up in a French knot (he only knew what that was because of Fred). Her face had plenty of age lines, but he could tell she had been a beauty in her youth. Despite her appearance, she was wielding the bow and arrows like an experienced archer.
"What are you doing, lady?" he yelled above the noise of battle. "It's dangerous out here!" He had noticed a few ordinary citizens peeking from windows of nearby buildings, or hiding behind dumpsters, but to see one of them joining the fight was baffling.
"Trust me, I know what I'm doing," she yelled back. She had a slight British accent. "Keep fighting!" With three well-aimed arrows, the woman took out the vampire he had planned to shoot and two of his friends. With a shrug, Gunn lifted his sword and went back to fighting.
A temporary lull came when Wilow arrived and took out a swath of demons with a fire spell, which temporarily held the army back, burning anything that tried to cross it. Connor, the least injured of the group, went to explain what was going on. Angel and Spike, showing many cuts and burns, limped over to the strange old woman and introduced themselves.
She looked thoughtful when they finished explaining the situation. "So you're vampires but you have souls? I guess that makes sense. I'm Susan St. Laurence," she said simply.
"Mind tellin' us how you got to be so bloomin' good with the bow?" Spike asked.
"I fought in a war when I was a teenager," Susan answered. "It was during World War II, but it wasn't in this world. My brothers and sister and I went to another world called Narnia, where there are talking animals and centaurs and fawns and dryads... all sorts of magical creatures."
"Sounds like another dimension like Pylea," said Angel. "Fred, our friend who is now that blue woman over there, lived in Pylea for five years."
"I was in Narnia for fifteen," she said, smiling nostalgically. "The four of us became kings and queens there, but we all went back to being kids when we came back to England."
"I thought you were a Brit," said Spike. "When'd you come to the States?"
"When I was 21, after my family all died in a train accident. It was too painful then ... I just had to get away from London. Then I ended up marrying a very rich man here, who died a few years ago. For a long time I actually convinced myself I didn't believe in Narnia, but I still remember how to use a bow and arrows, so it must have been real. Plus, if vampires and dragons are real, I'm not going to doubt the existence of other worlds anymore!"
"You're very strong," said Gunn, who was now lying on the ground with a magical bandage wrapped around his middle, thanks to another of Willow's spells. "I noticed one of your arrows go straight through one vampire and into another."
"Oh, yes... It's strange, about a year ago I got this odd rush of strength, and could suddenly lift things that I never would have been able to lift before. I also started having strange dreams about young women fighting creatures like those," she gestured toward the demon army, still held at bay by Willow.
"You're a Slayer," said Angel to Susan. "You must have been a Potential all along. Andrew said it wasn't just young Potentials that were activated by Willow's spell, that a lot of older women had shown up, some of them who had been trained in their youth but then abandoned by their Watchers when they grew up and never got Chosen. It basically means that you have a supernatural calling to fight evil." A green portal opened up nearby and some young Slayers started arriving. Angel saw Buffy and Faith among them.
"Those young women there are all Slayers," he told Susan. "They all have natural strength and fighting ability. I'll introduce you to them later." Buffy was now being debriefed by Connor.
"Oh," said Susan. "Well, I'll have to get a better explanation for that later, but for now I think it's time to go back to the fight." Willow, now looking strained, had signaled that she was going to lower her fire shield, and they all lined up to battle the demon army again.