Hmmm I think for Bibi it's currently Mithra's room SKDBJDKS it just feels private enough for it to be the two of them and Bibi may not admit it but they like being with Mithra alone :) though as things progress it becomes a place in the north where they happened to be at a few times and Bibi grew fond of the location because of how clear the sky was and staring at it while Mithra tried to drift of felt calming!