Most of the encounters between Twilight and Luna occur in the astral plane, a “place” where the beings that inhabit it neither look at them with fear nor worship them. Even though Luna has complete control of non-physical planes and their belongings, she didn’t get the “respect” of their supposed subjects. An issue the nocturnal goddess strongly refused to speak with her only friend.
 
Despite this, nothing stopped them from having fun together, enjoying the illusion of freedom, traveling by planes and alternate realities where they mostly got into terrible and never returned again.
 
Another one of their favorite pastimes was entering the dreams of ponies or dragons and alter them for fun, something that Luna always did by herself, but the experience was much more fun when someone was by her side, giving her ideas to torment the poor onironauts.