Mars in Capricorn gives a structured and contained behavior.
People with this placement are usually very disciplined, but they do need outlets to release some of the extra energy that is accumulated. Too much structure may make Mars feel relentless or even rebellious from time to time. The good side of this is that they can put a lot of energy in tasks requiring constant attention and focus.
In business, they’re good at analyzing large contexts and they do tend to involve in big structures or corporations, where they seek – and usually find, relatively fast – a position that allows them to control much of the power that is distributed in that structure. They’re not usually very visible, but they have a thing for manipulating power from behind the scenes.
As partners, they’re tense and intense. You may think you know all about them, and, for a while, that will be true, but form some point on, they will tend to create individual schemes in which you may or may not have your role. As long as you understand they need to create and exert power structures, you may have a good and reliable partner. If you do fit in their plans, of course.