"Is my new librarian a Watcher?" she asks Sherlock the day after Mr. Giles joins the faculty.
Why yes. Yes she can go faster than that.
She ramps up for rather a while before discovering how fast, and she grins at the blur of her hands.
"Cool," she says.
"Much better," he says. "You'll find that while plenty of nasty bitey sorts have superhuman speed, very few of them put it to good use."
"Fail to put it to good use how?" she asks, throwing in a kick to break up the rhythm of the punches. The air would be tripped, if it were not air.
"As simple as that: they don't use it," he says. "I don't believe I have any special physical advantage over other vampires, but I move and react faster than they do because I pay attention and I know my own abilities. They don't push themselves. Perhaps because they don't usually have to."
Bella pushes for a little extra burst of speed, which she can achieve but not sustain, and then she starts adding more kicks to the pattern, and then she spins once to make the front kick a roundhouse. "Don't vampires sometimes get into fights with each other? I'd think that would incentivize pushing even if most of them are never going to run into me or one of my predecessors. Or successors."
"They do, yes," he says. "But judging by how easily I kill them, they don't do it often enough. Try making that more level," he says of the roundhouse.
She adjusts the angle and tries again. "Some of them manage to live for hundreds of years. Have you tangled with many of those?"
"On the other hand," (she throws in a backflip that would snap any neck attached to a chin caught in her foot's path, then resumes her flurry of blows at the air from farther back) "hearing you talk I'd figure you for English. And you also fail to look six or seven years old."
She snickers. "Opinions on the backflip? I was so pleased when I discovered I could do that."
"Is it ever useful to be flashy solely for the purpose of being flashy? Does it scare people, or anything?"
"It can scare them, or make them underestimate you, or distract them. All very useful, under the right circumstances."
"The backflip would make someone underestimate me because...?" Her onslaught against the vile villain, The Air, is unslowing.
"It's flashy," he repeats. "If you consistently display unnecessary theatricality, you look inexperienced, or arrogant."
"Personally," he says, "I tend toward maximum economy of movement unless there is some reason to act otherwise. And yet I am probably among the most arrogant vampires on the planet about my fighting abilities—granted, not without cause."
"Yeah, I saw you, you're very good," Bella agrees. "Do you have any more notes about how I'm doing at beating up all this nitrogen-and-whatnot?"
"My comment is that you are good enough at beating up the atmosphere that you might benefit from a more substantial opponent."
Bella decides to see if she can obtain any value from whatever limited element of surprise she can get against Sherlock, and aims a kick at the back of his knees.
"Well done," he compliments, and counterattacks. Not at full speed. The point is to teach her, not to kill her.
Bella is going as fast as she can, and she needs to, to compensate for his skill and her lack thereof. Most of the aikido she watched involved working from someone attacking - she remembers this one throw - she tries it.