Lucy didn't really know Katie outside of what she had been told about the girl, which wasn't much. She knew that she was nice and sweet and a very good quidditch player, but other than that, nothing.
Hearing the knock to the door, Lucy stood up, turned to do a quick inspection of the room to make sure that all her art supplies and canvases and things were in proper order before smoothing out her skirt and hair and going to open the door.
"Hi, Katie." she smiled sweetly and held the door open so the other girl could enter. "I'm sorry if you had trouble with the riddle, I should have warned you."