Sigh. "Not your fault. Unless you've been making wishes around demons."
"I guess I'll just. Sit her down when Charlie's not home. Tell her."
"That... seems like it might be best. I don't know. I don't have the answers here."
"Yeah, I'm just - in case I have been mindcontrolled, instead of it being everybody else, seems like it might be worth the extra sanity check."
And Giles continues futilely researching possible causes for an extraneous sibling or a comprehensive memory deletion.
"Sorta? Uh, Bella says you can't, like, analyze me or anything, but I wanted to make sure?"
"Being a - something? Like, you can tell if somebody's a vampire, can you tell if I'm a human in particular out of the kinds of non-vampire?"
He spends some time fussing with Latin chanting and a quartz crystal and a bowl of water.
The water fills with a bright green glow. The quartz crystal glows in the exact same shade, brighter and brighter, and then shatters into dust.
"...I don't know how to interpret that," says Giles.
"Um. Did I break your quartz? I'm sorry I broke your quartz. What does it mean that I broke your quartz."
"At a guess, it means powerful magic," says Giles. "Powerful magic tied in some way to the colour green. But that hardly narrows it down, because we already established that powerful magic would have been necessary to delete you from Bella's memories or introduce you to the universe... I'm sorry that was so inconclusive."
"Sooooo it might just mean there's magic about me and not that I am it?"