They arrive at the professor's office. Johann knocks on the door. 

"Come in!" a voice calls from within. 

Johann opens the door. 

The woman inside is wearing something white and drapey in a manner sort of reminiscent of a chiton or stola but much more elaborate and with more actual tailoring than either. The garment exposes enough skin to show a pattern of green-and-grey scales running down from the back of the professor's head and over her back and shoulders. 

The professor is wearing a dark veil that completely obscures her face. Snakes extend from her scalp, some of them at rest along her shoulders or back, but more of them at least a little agitated, quasi-slithering in the air. 

"Hello," she says sweetly, hands clasping in front of her. 

"Hello. I'm Bella."

"What a funny coincidence," she laughs, "I'm Belladonna Agrippa. Using you as a divination focus will require looking directly at you, which will slow you down substantially for a moment; you may wish to sit down." 

Bella sits. "But it won't turn me entirely into stone?"

"No, I won't need to look at you that long." 

It is immediately perceptible when her gaze lands on Bella. It's not quite like being surrounded by syrup--she feels less like a thing that moves. Only a little bit, though, and only briefly, before the weight of the gorgon's gaze is lifted. 

"Oh, that's fascinating," the professor breathes. "Absolutely fascinating...I'm not quite sure what I expected, but not this." 

"...'this' being...?"

"Hmm. I assume you know little or nothing of dimensional theory." 

"You assume correctly."

"Have you ever heard of a Tesseract?"

"Only from people taking especially deadly math classes."

"...Did you glean any of the actual math, or just the vocabulary word."

"I am unsurprised that it comes next to the words 'dimensional theory' but I know nothing more."

"Alright. So--are you familiar with the concept that if you have a one-dimensional two-inch line, then the two-dimensional version is a square with two inches on either side, and then the three-dimensional version is a cube?"

"Yes."

"So, the two-dimensional version of a cube is a square, but there are ways besides a square to represent a cube in two dimensions." She picks up a tablet, fiddles with it for a moment, and holds it up, displaying an animation of a rotating cube. "This is called a projection of a cube onto two dimensions. A tesseract is the next thing up from a cube, and we can't properly visualize it because our brains don't work in four spatial dimensions, but we can mathematically derive that, projected onto three dimensions, and then projected again onto two, it looks about like this." She fiddles with the tablet again and displays another animation. "So something that appears to be surrounded, from a two-dimensional perspective, isn't surrounded from a three-dimensional perspective, there's a whole other dimension for it to have neighbors on. So there's a set of dimensions where the set of physically contiguous places you can get to on the material plane with its three dimensions is basically a bubble, and there's a set of other bubbles surrounding it, in what you can imagine as a series of concentric spheres even though spheres are three-dimensional objects and we're operating in higher than three dimensions. And then where you're from is adjacent to us on a different set of dimensions than the ones we're used to varying!"

"...gosh. Okay. What practical upshot does this have for reassuring our families and setting up interdimensional trade?"

"It should be possible to get to where you're from but it should be managed carefully because contact between these two planes has never happened before which means there isn't a set of standard precautions known to be necessary or not." 

"We do have a known infohazard situation and I currently do not know to what extent it applies here at all or to witches visiting our world."

"--Well, you're going to have to tell somebody about the infohazard situation, going into a situation with unknown infohazards is not something you survive being willing to do for very long."

"Is there anyone who already routinely adjusts their memories and wouldn't be bothered by doing it again for this purpose?"

"Yes, we have infohazards to and various precautions against them. We also have divinations along the lines of, 'I'm planning to do X, is that going to go incredibly badly.'"

"For this purpose that should probably do."

"Alright, give me a moment." 

She picks up her tablet again and fiddles with it for a bit, and then a portal about the size of a salad plate appears in mid-air and what appears at first glance to be an unusually chunky moth flutters through it, before she perches on one of the fixtures in the room and it becomes apparent that this is a very small humanoid with pink and yellow wings. 

Belladonna says, "I'm going to leave the room with young Mr. Morgan here, and you can tell Felicity your infohazard. Is the plan that I cast an augury on. Does that sound good?"

"Uh, sure."

"It goes fine. Do you feel comfortable proceeding in reality?"