Mercury represents your mental functions and your urge to communicate. The sign it is shows how you arrive at your opinions, how you hold onto your opinions, how you communicate them. Mercury does not indicate how intelligent a person might be. The house that Mercury is in indicates where the person directs their thoughts and communication. The aspects with other planets have a very strong influence on mental functions, modifying the planet-sign-house reading.
Mars represents our desire nature. How we feel our desire, how we react to it, how we go after what we want, and how we react when something or someone gets in our way. Therefore it is associated with initiation, action, courage, anger, and sexual desire. As with any other planet, sign & house are important, but even more important are the aspects to other planets in the chart.
