Air and earth think differently: one lives on ideas and motion, the other on results and consistency. With respect, they complete each other — one's ideas land thanks to the other. Without it, one feels tied down and the other dizzy. Translation is the key.
Two mutable signs: infinite adaptation, mutating conversation, plans that change without drama. The hard part isn't getting along — it's deciding. This bond does well when someone says 'this, here, now' once in a while.