Ask if their moms are together

"You keep talking about about your moms. Are they together?"

The pair frown. "No." River says.

"My mom just can't see how hot River's mom is." Skye shakes her head.

River snorts. "More like my mom is jealous of how sexy her mom is."

Skye rolls her eyes. "It's not that bad though."

"They used to hate each other."

"And my mom hated River."

"And my mom hated Skye."

"Wait, I can understand hating the other woman in a love triangle, but the daughters?" you interject.

"She didn't like how River would always grab her breasts as a kid."

"She said I had inherited dad's perverted nature. And my mom always hated how Skye would talk about how beautiful she was."

"She thought I had inherited dad's casanova tongue."

"But they couldn't keep us apart."

"We hated not being together."

"And we'd always find each other again."

"See, we've got a twin link."

A twin link was a common magical mutation, usually among twins, hence the name. It had varying levels, but twins tended to have the strongest ones. People who had it could have a few properties, but common were sensing locations and emotions, or even telepathy.

"Eventually they accepted it and moved in together."

"They still didn't like each other though."

"By the way, we need to ask him that."

"Oh, right. Which of us is cuter?"

"It's Skye, right?"

"You prefer River, don't you?"

"Uh..." you had never had to choose between two women before, and especially not ones who wanted you to pick the other. "Oh look, Headmistress Kess is standing."

"Witches and wizards in training, I am Headmistress Kess. You have all come here to deepen your understanding of magic, but also, I remind you, to deepen your understanding of your classmates. For this purpose, as always, students are required to form Bathas, to foster cooperation between the Houses. I also remind you not to focus so much on getting to know your friends that you forget to go to final exams. Petunia, Alex, Peter, Xavier, Eli, Francine, George." She looked from table to table, presumably at the students who had done that. "The first year students can only go into town on weekends, and all students must have permission from a professor before leaving campus. Duels are permitted only when supervised by a professor who has agreed to the duel. You are not allowed to hurt your opponent, or fellow students. I can't even believe I need to say that. Finally, I encourage you to ask for help whenever anything goes wrong. Both myself, and your heads of house are always available. We won't judge you, we have seen worse, and we won't tell you about it. There is a door to my office in common areas of every house, and for those of you who notice that that's impossible... welcome to Alexandria, try not to get lost." There's some applause, and you use the commotion to stand up.

"Let's go get some food," you say, and hurry off.

"Nobody ever answers that question." you hear from behind you.