In almost every roleplaying game the players attract followers. The have hiringlings, helpers, lackies, etc. Over time people fall under their sway and armies will march under their banners. This is because most player characters are, by the nature of the game, special. They are the heros (or villians) that stand out from the crowd and do great things.
Loyalties are fickle, however, and can change based on a whim. What sort of actions and interactions can change how NPCs feel towards the PCs? What realistic motivations will keep your squire with you while all others have fled? What might cause the trusted general to betray his leige?
The NPCs in the party, group or unit, as well as contacts, allies, and friends, are the ones who see the character on a day to day basis. They have the advantage of being able to judge for themselves first hand what kind of person the character is. They are most influence by the direct actions of the character in their presence.
Similarities: The NPCs will tend to like people who are similar to them. They may be countrymen, they may share the same code of honor, or maybe they just both have similar hobbies or the same sense of humor. Just as in real life, the similarity might be so slight that even the two people in question can't put a finger on it, but there should be something.
Goals: NPCs may be personally loyal to the character because of similar goals or needs. Sometimes this lasts beyond the accomplishment of the goal, or if there was no other bond there, it could have been an alliance of convenience that is soon forgotten. Everyone has seen the theme where two enemies must work together against the greater threat. If, however, while working together there are other things the NPC has in common with the player, their loyalty may become more permenant.
Greed: Money, wealth, and power are all strong motivators. If the NPC sees an opportunity to gain from an alliance with the character, he will be loyal, after a fashion. The danger here is that there is always a larger prize that can sway the loyalties of the greedy. Of course, it need not be overwhelming greed that motivates an NPC. Most NPCs are just normal folks trying to earn enough to feed the family/buy the farm/retire/etc. There is a certain loyalty to the hand that feeds you and not all NPCs will jump up at the offer of simply a few more coins.
Charisma: The personal magnetism and looks of the character can attract the loyalty of NPCs and is typically the first measure of how an NPC will react to the character (since the NPC will know very little about the character upon first meeting him). This kind of loyalty can range from the superficial to deep seated affection.
The masses are a step removed from the character and so don't usually have a personal knowledge of who he is or what he does. This dilutes his influence. Media sources often have tremendous power to pursue their own agenda while waving the flag of "impartiality." Rumor has the wonderful tendancy to shift change as it travels. Subordinates who act in the name of the character, but act differently than he would can color the impressions of the people.
Similarities: People like to follows those who they see as similar to themselves. This will tend to manifest itself in more obvious ways on the mass scale: religion, nationality, political party, social group, etc. Catagorizing is easy to do and hard to overcome. This can either bolster or hinder loyalty to the character.
Goals: Leaders are defined by their "vision." Again, sweeping statements are often more influential with the masses than the details. This is still a fairly week sort of loyalty on it's own. What happens once the goals are accomplished or if the plan fails despite the character's best efforts?
Greed: The masses can often be swayed by greed. Offers of prosperity in the land can take the form of tax relief, public programs, promises of better jobs and more wealth (often without facts to back them up). A problem with this is that promises come quicker than results and often all it takes is someone else with a better looking program to usurp your power base.
Charisma: The cult of personality is a very necessary one when dealing with the masses. Personal tours, portraits stamped on currency, media releases, public statues, etc. all serve to enhance the charismatic appeal of the leader, making them larger than life and everywhere you go. It is in these forums that the character's personal charisma has the opportunity to sway the masses.
Soldiers are very much like the masses in how they react to their leader, but with one important exception: they may die because of this man. Faced with that sobering realization, soldiers tend to be wary of where they place their trust and loyalty.
Similarities: Like the masses, the armies will follow those who are similar to to them in nationality, faith, etc. Also important is the character's background. If he has served in the military or is still a soldier, he will garner greater respect. Should he have a history with a unit, often that unit will support him out of tradition.
Goals: Missions and goals that the soldiers agree with and understand are often good for morale and loyalty. However, should the leader decide on goals or missions that run counter to the sensibilites of the soldiers, their morale and loyalty will wane with each botched plan.
Greed: Bounties, salaries, salvage, land rights, slaves, titles... all these things are offered to soldiers in order to convince them to serve. As always, the allure of wealth is fleeting if there is no deeper sense of loyalty to the character.
Charisma: A character who endures the same hardships, visits with his troops, and shows a personal interest in them will greatly enhance the effects of his personal charisma on the loyalty of his soldiers. Many are the examples of armies seemingly driven on by the will of their commanding officer alone.
Betrayal can take many forms. The NPC may offer less than his full effort to aid the character. He may decide to remain neutral or absent when a key situation arises. Enemies may gain support or aid from the character's erstwhile allies. The most extreme result is that the NPCs openly and actively campaign to thwart the character.
Differences: The character is from a rival nation, faith or group. He behaves in a way that chafes the NPC. The NPC does not agree with his view on the world or on politics. Maybe the NPC just doesn't like the kind of person he is.Goals: The NPC and the character either have different goals or different ideas on how to achieve them. Sometimes this simply means they have no reason to work together. Other times the goals are opposing, placing the NPC and the character in direct conflict.
Greed: The NPC has been offered money by a rival of the character. He has been bribed, is in the employ of an enemy or simply sees more profit in bringing about the downfall of the character. Often times the NPC simply sees no incentive to follow the character, or the reward isn't worth the effort.
Charisma: The character may simply not be a people person. His appearance may not bring out feelings of trust or loyalty. His manner may be abrasive or harsh. Perhaps something the character said without thinking had a deeper effect on the NPC than he thought.
Let me conclude by saying that I am not a psychology major or a professional in human social interaction. This article is based purely on my observations and experiences. The positive to that is it is in layman's terms. The downside is that it's not a complete analysis. That said, feel free to use or discard the information herein.
As always, feel free to send corrections, feedback, etc. concerning this article!