Hey, good dialogue here! Having two established characters with very different personalities, plus one newcomer, made for some fun interactions. I especially liked the part where Carlisle tried to say Billy Simpson didn't work in Potterverse, then Fáelán pointed out how subjective that could feel, based on the setting. It's nice to see different perspectives clash! I hope Émilie is picking up some learning, in spite of her wandering concentration and spider-based distractions . . .

Two typos, one sentence after the other!
However, over plates of mercifully decadent Potterverse food prepared by the House-elves, the agent soon forgot whatever was bothering them and began to have a pleasant little chat.

“These pork chops are good,” Émilie said. “The lemon juice really accentuates the umami notes.

"Agent" should be "agents" to match the "them" pronoun after. And Émilie's quotation marks never got closed.

—doctorlit, ready to start his final nap of the weekend