It was the Knave's little habit to search for your figure every morning when she walked around the Zapolyarny Palace. You were most likely running to do errands for the other harbingers.

"Ah. Thank you for running a bath for me, my dear..."

The Fatui's most loyal maid... That was you. So there's no reason why her asking for this...

"Could you wash my back for me?"

Should be weird... Right?