There's a pattern here. She knows there is. But it's subtle, it's so subtle she thinks she might be imagining it. A flyer appears on the wall of the coffee shop, announcing that his band has a show there that week. There's so few details that she thinks she must be mistaken, someone else here must have decided to use that same band name, it wasn't that creative- but she goes back to look again the next day, just to see, and it's gone.
She finds a jelly doughnut left on the hood of her car while she's out shopping. They're Kevin's favorite, and she has to talk him out of eating it- they don't know where it came from, it can't be safe, just throw it out, see how someone's already cut it open? It's oozing red jelly out over the roof of the car.
Little things, one at a time. Spaced apart enough that she's never quite sure they're related to each other. A week before something new happens? Two? Once there's two incidents in three days, then nothing for almost a month. She could be imagining it.
...maybe.
She finds a stuffed dog in their front yard. It's very generic, one of those silly plush dogs you can get at any store for a few bucks, and it's arguably, plausibly, a dog toy. But the tag on the dog's collar says 'Tammy'. And it's been torn almost to shreds, viciously. And none of her neighbors have dogs.
Tamara calls the Watcher's Council. And then she calls Bella.
Bella's shell knife will make short work of the chain. She does her best to keep it quiet.
Bella stalks towards them, shell in one hand, stake in the other - indoors she's probably not going to get the freedom of range she needs for the crossbow to be her best option.
Tamara digs out her emergency stake from her purse and follows them, at her best guess for a non-interfering distance.
"I don't understand why you won't-" the man hisses, and then turns around. It's definitely Charles, though his quick switch to vampface obscures his features somewhat. "You- what!" He says in Tamara's direction, ignoring the girls. "How did you find me so quickly?" He sounds deeply put out, and rather whiny. "Time to go, then." And he bolts for the door on the far side of the room.
Once he moves, Kevin gets a better view of them. "Mummy! Mummy help, let me out!"
Soph dithers. "Bella will be back with her shell knife in a second," she tells Kevin, "and then she can get the chain off you -" And then she goes after her sister.
Tamara runs over to Kevin. "Kevin, sweetheart, you're here, I'm so sorry, I don't know how he got you, it'll be okay now-"
Tamara breathes a sigh of relief. "Yes, sweetheart, I'm here." She kneels in front of him. "Hang on, let me see if I can get you loose-"
(just in case, in case charles attacked her, in case something happened)
Halfway through Kevin's lunge, his chest meets the stake Tamara's holding up practically by reflex.
(all watchers have to practice, watchers should know how to stake, what if a vampire finds them, what if the slayer's hurt, what if something happened)
With a cry, Kevin crumbles to dust.
(her baby boy, how could charles take him, he was all she had left, how could something happen)
And Tamara collapses, unable to stand, sobbing hysterically into the floor.
"Fan out," Bella calls to her sister, and they take different directions through the debris. Bella has no supernatural senses to guide her, but she was very close on his trail and she is very fast and nimble. If she's wrong about where she's going Soph still has a shot at setting the guy on fire once they get into more open ground and the line of sight is better.
After a short time it may be obvious to those keeping pace that he's headed towards an exit towards the back of the building. Since the back is on the west side of the building, there's some shelter from the sun still. And, more relevantly, an entrance to the Sunnydale steam tunnels.
"I'm out," she calls to Bella, "go on -"
And then she hops back to where Tamara and Kevin are supposed to be -
There's a Tamara here, at least. She's still on the ground sobbing, and trying to nudge a scattering of dust into a more coherent pile.
And she finds a shortcut - there's a chain strung high across this path, high enough to be awkward to jump and heavy-draped enough to be hard to go under, but she has her shell knife; she cuts, she runs, she intercepts.