Arousal
It starts in her toes. A tingly feeling, almost painful, like pins and needles when she'd stand up after a particularly grueling algebra class.
It crawls up her legs, and that's exactly how she'd describe it, it crawls. Like spiders just inside her skin, something she never saw happen but she looks down anyway, because hey, this is Sunnydale and the Hellmouth is opening up again. No spiders, no creepy movement under the skin. Good.
But the tingly feeling, the pins and needles feeling, is in her thighs, and between her legs. There. She doesn't know but when the tingly feeling just jolts up her torso from there, it might be just like an orgasm. It might be. She'll have to ask, later...
Her arms are poised in the air, holding a broad sword, ready to swing at whatever nasty uber-orcs - uh, vamps - decide to come at her. And now the sword is so much lighter, and her hands are no longer sweaty from gripping it so tightly. That strange feeling sweeps down the backs of her arms and back up the inside. Her shoulders and her neck are getting the most pleasant massage that doesn't relax her, but stiffens her, makes her ready to pounce.
Pounce, she thinks. I could actually pounce.
She bends her knees a little. Once, twice, and the power she feels tells her she could do a hell of a lot more than pounce.
The feeling crawls up her face and her nose twitches and she wants to scratch it, but all thoughts are lost because the tingly feeling explodes right there, stretching her brain until she isn't sure if she'll survive. She squeezes her eyes shut. Her mind expands, she sees light, all of this is some kind of wonderful but she almost panics.
Was this some evil trick of the First's?
And now her mind is racing. No, no trick. Just a spell.
She opens her eyes, and a vamp is coming right at her. He smells, she thinks, like blood and rotting flesh and a little like that girl who slept with a blue blanket and always asked for grilled cheese sandwiches.
She yells, partly in pain because now this is personal.
She swipes down hard with the broad sword, and she must have hit the heart, because dust explodes and the vamp is gone.
A smile spreads across her face.
She swings the sword with one hand to take the head off another uber-vamp.
Piece of cake.
Later, when Willow is speaking in her trademark awed voice about the power of the Slayer awakening all the Potentials, Dawn just smiles to herself.
Because she knows exactly how it feels.