She may get an idea of where Berenike thinks they should start from the varying intensity in her shiver reaction to the taps of the knife.

Well, that seems as good a signal as any. 

She starts cutting - nice and slowly and carefully, right where Berenike gets the most shivery about the idea. 

She stays very still, hissing out a breath.

"You're so beautiful like this."

"Nn. You look dangerous."

"That's because I am, lovely girl."

"I like it."

"Good." Bitey kiss.

Berenike is so on board with making herself bleed.

Convenient, because she'll be doing a lot of it here...

As Seshen wishes.

Meanwhile, Eleni sees to her own slave.

Who kneels when Eleni enters the room. "What may I do for you, my Mistress?"

"Sit with me, pretty thing."

She rises again and comes over to her Mistress, sitting pressed against her. "Did Hypatia's chaining go well, Mistress?"

Pet pet.

"Almost too well, in fact. My flower's loyalty spell seems to have given her an entirely new personality. She remembers nothing of her life before today."

"You believe her?"

"Seshen tested her. Berenike, as she is now called, is telling the truth."

"And Hypatia would never condescend to the display I witnessed."

She makes a curious noise. 

Eleni can describe the scene in great detail for her.

"Oh."

"I would love to help further testing, Mistress."

She laughs. "I thought so. Once Seshen has finished her initial inspections, we'll see about having you two introduced."

"Thank you, my lady."