Wicked Headcannon Thingies
Glinda and Fiyero bring Elphaba with them everywhere. They never even think about not inviting her when they go places and they see nothing weird about it until something points it out. Whenever they do try to do something without Elphaba all they can think about is how much they wish she was there and whenever she's left alone for too long she ends up getting into some sort of trouble.
Whenever Elphaba and Fiyero are left to their own devices they will inevitably end up doing something dangerous or illegal or both.
Glinda is very dramatic about it.
Boq mentally refers to Elphaba and Fiyero as Headache 1 and Headache 2. He was not thrilled when they decided to start working together.
Nessarose has made the executive decision to stay out of any and all of the peril, chaos, and shennanigans that seem to follow in her sister's wake unless someone is actively dying.