When they come across Janet, Janet is surprised, and -- much to her chagrin even as it's happening -- a little awkward. At least Lucy is almost an adult, not a little kid, but Janet's just not good with anyone younger than about twenty anymore. She does her best, which is a huge testament to how much she likes Susan, and she indulges every question Lucy might have about Fillory. That's easy enough, because Janet fucking loves Fillory. Even when she's describing something stupid, like the way you can tunnel through the swamps to get to the opposite side of the world, and when her tone is disdainful and irritable about how stupid that is, her fondness shines through.