Slayer Essence

The First Slayer hadn't been very subtle, nor had most of the Slayers who followed her, in anything other than fighting style. To them, the world was divided between humans to be saved and demons to be slain, black and white with no grey areas, and nearly all of them – especially those who survived a significant period of time once they passed from Potential to Slayer – had been raised by the Shadow Men or the Watchers or whatever they were calling themselves at the time, their lives containing nothing but duty and learning everything they needed to know before they were Called.

Buffy Summers and Faith Lehane were birds of an altogether different feather. They'd both survived longer than most Slayers survived, neither of them with the sometimes-dubious benefit of being raised by the Watchers. Both knew how to take pleasure in life, even while doing their duty. They knew how to be subtle, how to blend in, and that not all demons were evil and not all humans good. They had a wealth of experience most Slayers never even dreamed of getting, from the best of life to the worst of it. Dead, their opinions carried considerable weight.

The Slayer essence changed then, like it had never changed before. The system had worked as it was – the world was still there, wasn't it? – but Buffy and Faith made the rest of the dead Slayers who were now part of the Slayer essence realize that just because it worked, that didn't mean it couldn't be improved.

From then on, Slayers got more dreams from the Slayer essence. Not prophetic – the essence couldn't control when the Powers handed those down – but from the essence itself. Extra training in the girl's weak points, from concentration to fighting style to tactics to demon recognition to having fun. Encouragement. Somebody to talk to. A shoulder to cry on. And while they were awake, a small voice in the back of their heads, giving advice. Of course, the Watchers congratulated themselves when the average lifespan of the Slayers went up.

It was more difficult to communicate with Potentials – since they weren't Called yet, the connection to the essence wasn't as solid as the Slayers' connection, and there were so many more of them that it wasn't worth the extra effort to give them the deluxe treatment the Slayers got. They got dreams, but for most of the Potentials they were vaguer and not as personalized (if they were in a bad situation or had a lot of stress, the essence made an extra effort for them). But mostly the essence influenced them by giving them nudges: to be at least initially interested in martial arts of some sort, to stay in shape, to judge people on their personality rather than their outward appearance, to have fun but not forget their responsibilities.