Aquarius and Gemini are both intellectuals who love to learn and communicate their ideas. Geminis are ruled by Mercury, the planet of communication. Aquarius is ruled by Uranus, the planet of change and innovation.
In Aquarius, Gemini finds a soul who wants to make the world a better place and will stand by them regardless of the consequences. Aquariuses are independent, eccentric, and a little out there, but Geminis love that about them.
As long as Aquarius gives Gemini the freedom they need and Gemini allows Aquarius to be individualistic, this connection can be highly successful and last a lifetime.