Gemini and Scorpio are very different in their energies as people, in their goals, how they relate in love, what they're looking for in life. Gemini is an air sign, meaning it's communicative and curious and spontaneous and essentially wants to get out. In other words, to experience, to explore. Scorpio is a water sign, very, very feeling and very intense. The major characteristic of a Scorpio is control. It does not want to have or be in a relationship in which it, he or she, cannot control the other.
So immediately they do have a passionate and fabulous sex life. Immediately. Because Gemini loves to explore and to titillate and to flirt with and to find new sex tricks. This, of course, empassions a Scorpio who is already a very sexual sign. So there's lots of fireworks, lots of tempestuous lovemaking.
Then they move on into the next part of the relationship, where they have to make a go of it as friends. There it's more difficult, because Scorpio does control intensely, does fell intensely, and tends to be very temperamental in its attitudes.
Gemini doesn't have time for this, really doesn't want someone who is constantly in a negative frame of mind or who constantly needs to have the rules followed, or the situation of being too much under the thumb of another. So Gemini tends to wander off a bit, goes out dancing or socializing, and Scorpio sits and home and seethes.
Basically, long term they are going to have a lot of conflict between them and hostility between them. Best if they could form a friendship first, and then fall into a love affair. But usually that doesn't happen.