Courage is directly related to the amount found in your leader. As a sidekick, you don't speak for yourself, but both words and actions. It has been known throughout the history of the world that once a leader or commander has been overpowered, then the rest of his crew (however large) will crumble. And if it does hold on to some hint of life and manage to survive the ordeal, they will at least be in disarray unless a new leader is appointed fast.
Knowing this, choose your leader wisely. It is him/her who speaks for your congregation and whatever he gets you into, it now your problem. Therefore, your battles are those of your leaders courage.
Leaders have special abilities that come with the job, like +2 fortitude, +3 persuasion and a whopping +7 to diplomacy. Leaders have the power to imbue courage among his subjects, but also can take it away. It is there other actions that help them get more boosts to their stats.
A wise sidekick once said, "Make sure your top-dog knows all elements of the map and scenario. If you do this, then your party will be one that will lead to great fortune and vast experience."