You had recently gotten a letter from Sucrose to meet in her lab, with the letter noting to meet her when nobody else is around. Perhaps that's just more comfortable for Sucrose, as she's quite introverted around other people. Kaeya had remarked she's more wild in private, but surely nothing bad would happen...right?

First step in, and she's already leaning against you. "Thank you for coming over. It's not often I have someone to do experiments with."