My family says I'm a Category 5 hurricane. I have both Mercury and Mars in Gemini. I am literally a ball of energy at times and I kind of feel sorry that people have to deal with it. Even if I'm sitting quietly on the sidelines, everyone can feel my presence and it can be very unnerving for them. It doesn't help that I have a very direct gaze (grey eyes) - I am perceived as scary intense and mysterious.
My sisters - we were orphaned so we're very close - chose "mysterious" as the one word to describe me - I was kind of shocked. And here I thought I was an open book. lol
I want respect, solitude, to be appreciated for the things I do for you, fairness and freedom.
I get what I want with direct action.
I am logical, rational, relentless and fact-driven when fighting with you. I will also verbally draw blood if you are disrespectful or you humiliate me. I hate a liar with every fiber of my being.
Talk dirty to me, baby. Love to experiment. Am the initiator quite frequently. Love clean sex.
I love words.
The one I know is very energetic/active. Always juggling multiple tasks 
. They have Mercury in Gemini also, & are very astute and observant.
What do people with Mars in Gemini want?
-Knowledge, knowledge, knowledge.
-Learning something new every day.
-Love reading. I read more than one (non-fiction) book at the same time...Need lots of focus to complete a book though once I feel I've gotten a lot from it.
-Communications is a huge drive.
How do they get it?
-Research and planning. Strategizing.
- Via persuasive communications, asking questions and making requests.
- A great radar regarding where to study and who to study with.
How do they fight?
- Via cutting words (do this less these days)
-Via a great memory (for trivia, data and research/sources/papers) that is then used in persuasive arguments. Good at linking concepts and ideas quickly and good at increasingly building a persuasive case with evidence.
- Using sharp language to clearly hint to someone to back off
What about sex?
- Initiate it most times
- My mind is my erogenous zone so getting my mind excited with interesting conversation and flirting gets me ready.
-Tried dirty talk. Didn't work for me.
Cheaters more often have Mars in Gemini, due to the duality of Gemini; double sex life.
When aspected by Jupiter .... well you get the picture.
p.s. Before anyone takes this personally, please note that I am not calling anyone with Mars in Gemini a cheater ... this is merely an astrological possibility!
I can see that being possible, yes, with the Gemini curiosity/not wanting to miss out/short attention span side...not sure about double life yet Gemini is the twins, right?
The one I knew had it conjunct their AC too and was a MAJOR cheater. Multiple. All the time. While in a very long-term relationship. He once told me he had cheated with a female friend while his girlfriend lay next to them. Sneaky, clever, charismatic, never seen a better liar. Sex on the mind all. the. time. Even said he thought he might have a sex addiction problem. Addicted to web cam porn, fantasising about risky behaviour (doing it in public changing rooms, places you could be caught), threesomes, etc. He cultivated a persona where most of the people closest to him have no idea he is like this (even guy friends). Married the girl he cheated on for like 15 years. People believe they're a perfect fairytale. That's the sex/clever sneak stuff. Lots of what soup said sounds familiar too. Non-stop energy, 'sleep when I'm dead', insanely curious, on the phone texting people all day long from wake til sleep. Communication communication communication. A very charming, sexy, funny (eek, dangerous!) trickster who knows exactly what to say to get what he wants, whether that's going after somebody or lying to cover it up. Said "I just want a fun life!" Life motto was 'YOLO'