Libra and Sagittarius
Libra sizes up the room first; Sagittarius is already on the other side, talking to someone. Still, they take to each other almost instantly. Libra relaxes because Sagittarius doesn't make a drama out of someone else's opinion; Sagittarius settles because someone is actually listening to him to the end. It sours over obligations: Libra expects agreements to be honored, Sagittarius changes his mind along the way and sees nothing wrong with that. Fewer promises, more kept — that's this pair's whole job.
Libra · Air
Most in harmony with: Gemini, Aquarius, Leo
Sagittarius · Fire
Most in harmony with: Aries, Leo, Aquarius
The harmony of two signs is the beginning of the story, not its end — the whole chart, not just the Sun, tells how two people truly meet.