The angle between your signs — the square (90°)
The square is the aspect of tension: you want the same thing at the same time, just not the same way. This bond never falls asleep. It asks you to pick your battles, and makes you both stronger when it holds.
Your elements — Fire and Water
Fire acts, Water feels. One wants to move forward, the other wants to know what lies beneath. Steam, in every sense of the word.
Your rhythms — mutable and mutable
Two mutable signs: you both adapt. Anything is possible, nothing is set — sometimes someone has to decide.
Your rulers
Sagittarius and Pisces are both ruled by Jupiter: expansion and faith, lived in two ways. The same engine, two ways of running it.