In astrology, a planet's domicile is the zodiac sign over which it has rulership. The planet said to be ruler of Gemini, or those associated with Gemineans, is Mercury.
Gemini were the twin brothers Castor and Pollux in Greek mythology, also sometimes known as Iabal and Ivbal.
There are many variables in the astrology chart that determine compatibility of individuals. The position of the Sun, the Moon, the planets and the aspects they form with each other are assessed by astrologers before judgment on compatibility is made. The signs listed as compatible with Gemini do not reflect an individual profile or individual reading as interpreted within astrology, but rather reflect a general guideline and reference to compatibility as dictated by variables such as Qualities and Elements within the Zodiac. The branch of astrology dealing with interpersonal compatibilities is called Synastry.
^Mayo, Jeff (1979). Teach Yourself Astrology. London: Hodder and Stoughton. pp. 38–41. ISBN0340277440.