Traditionally, Air and Fire
combine well, since Fire needs Air to give it oxygen and stay alive, and
Air gets rather stale without the heat of Fire to get it moving. Likewise,
Water and Earth are traditionally considered compatible, primarily
because they rest easily in each other, the Water finding containment in
the Earth, and the Earth becoming either mud (if the Water is excessive)
or fertile soil that can produce abundantly.
Signs of the same element are the most compatible without any effort,