In Gemini, Jupiter makes for a playful, sometimes shallow but very creative approach.
People with this placement are cheerful, they can make other laugh pretty easy and they tend to see the laughable part in any event. They can be really good travel partners, for they tend to never get bored. Somehow, they’re always able to find an object for their attention.
On the less pleasant side, this attitude can make them a bit shallow, or at least, it can make them have a shorter attention span than you would expect. Their curiosity needs to be fed and so they tend to jump fairly easily from one topic to another, from one place to another or from one relationship to another.
Some of the risks of this placement are emotional instability, fear of commitment or even promiscuity. If natives decide to transmute some of this diluting energy into some sort of an artistic activity (writing would be really good, if supported by other aspects in the chart) they could become a bit more manageable. Also, they tend to be fairly successful in any artistic related endeavor.