Dawn's hard at work translating the Hermetic secrets of an ancient Egyptian priestess when Fred pokes her head in her office. "Dawn?" she asks. "I have a sort of weird question to ask you?"
Fred's been working on the same project, but from the other end: trying to recreate the original alchemical processes using her modern-day knowledge of physics, chemistry, and--of course--magic. Dawn, who got a B- when she took Calc I in college, doesn't understand the math at all, which apparently involves something like multiple-eigenstate transcendental numericality, or some such; too many nights begin with Fred trying to explain it to her in bed and Dawn desperately trying to distract her into silence by making love. Sometimes with somewhat questionable success.
"Erm, okay," Dawn answers, uncertainly. "Shoot."
Fred looks nervous. "So, um, you wouldn't possibly be a mystical nexus of energy, would you?" She takes a deep breath and then suddenly she's talking very, very fast. "You see, I was talking to Buffy about our experiments and the way there keeps on being this anomalous distortion in the magnetic fields and I couldn't figure out what it was and then I said--just as a joke--unless you were really a mystical nexus of energy and then Buffy got real quiet and said I should talk to you."
Dawn bites her lip. Her Key-ness isn't exactly a piece of information she likes being shared; then again, she'd also rather not lie to Fred directly. Especially if it's applicable to their research. Plus, you know, relationships being built on trust and all that. "Yes," she admits at last. "I am a mystical nexus of energy." She waits, holding her breath, to see how Fred will react.
"Ah," says Fred, sounding more interested than shocked or disgusted, and she starts scribblng new equations on her clipboard. "That explains a lot, actually."
The reaction is so Fred, so refreshingly characteristic of the scientist to care more about the physiocosmological implications than the fact that her girlfriend and lab partner isn't actually real, to react to that datum with nothing more or less than her usual intense scientific curiosity, as just another piece of information to be logged and tabulated and if possible integrated into the existing models, that Dawn can't resist laughing. But of course to Fred this flesh-and-blood world always has been an illusion; it's the constancy of the rules, both mathematical and metaphysical, which undergird it in which she trusts as the truer reality.
Fred looks up from her clipboard, confused. "Did I say something funny?" she asks.
"No," answers Dawn, then adds, "I love you."
Fred blinks, caught off-guard, then smiles. "You too," she replies.
Dawn grabs the other woman by the arm and pulls her into the office. "Come here, I have something I want to show you," she says.
"Did you make a breakthrough in your translation?" Fred asks interestedly.
"Not exactly," answers Dawn as she shuts the office door behind Fred and closes the blinds.
Moments later, and neither science nor antiquities is on either woman's mind.