As seen in the manga, Roy is a rather complicated man. Whether you spend five minutes or three hours with him you will know nothing about who Roy Mustang is, or why he ticks. Part of his intrigue as a character is precisely that Roy chooses who he wants to be known by, and how he wants to be known. He is quite adept at feigning a calculated persona for bystanders. Such a facade is Roy's defense mechanism for keeping people from getting close to him, while simultaneously concealing his true motives for his actions. For those who can get to see past his facades, if only even barely, they find themselves captivated and inspired by Roy and are unable to abandon his side.
The most prevalent characteristics that resonate, both internally and externally, through Roy is his relentless and tenacious determination. He does not give up at anything. He follows his convictions until their end. Roy does not know how to give in, fold, or succumb to defeat. Roy also has an innate and keen sense of leadership, which is provided and enhanced by the great respect he is able to ascertain and utilize, from both his allies and enemies. Roy's intelligence is also, not surprisingly, far above average (as can be seen in his tactical and quick rise through Military ranks as he simultaneously conducts his secret ambitions/plans). Roy has a penchant for not only bringing undying loyalty out of people, but also for reciprocating such loyalty to such people, as well as to the duties he's placed upon himself.
Roy is also able to learn from every experience, encounter, and every win and loss he receives. Such a trait again, makes his adept at adapting. Such adaptation allows him to not brood/live in the past, which considering the trauma sustained in the Ishval/Ishbal Rebellion, remarkably keeps him focused on his goals for the future. No matter how hard how deep the pit he's fallen into, or how difficult and emotionally wrenching the situations get, Roy always moves forward. He always moves on. He refused to let himself succumb to defeat or emotional breakdown. In addition he is able to model and reflect such strength and hope into the people around him. Roy is nothing short of a visionary (and an idealistic as well).
Further, Roy is an extremely polite person and treats people with the most respect, regardless of age, sex or race. How well he knows a person is also irrelevant. Despite his polite etiquette, he tends not to be straightforward. Straightforward in so far as Roy likes to be careful with words, and uses language as delicately and as precisely as writers would. For the majority of his words, there's much more meaning (or a double meaning) than what is said. For others around him, it takes time and experience to know what Roy Mustang is really talking about (as it does for us readers as well ^_^).
Roy is probably most misunderstood, ironically, by fans and readers, than by his fellow manga characters. Though the WebMasters believe this misunderstanding is a result of his portrayal in the anime version, more so than from the manga. Roy is often regarded as highly manipulative, arrogant, cold, and lazy. Roy is far from manipulative (at least towards the people he considers his friends or allies). Roy cares deeply for those his is close to and always makes sure everyone knows what they're getting themselves into and that it's their own decision and no one else's. This is not to say that there are times when he hides some information from them, but such decisions are never out of malice, but, because he considers it best for those concerning the mission (best for them emotionally).
Roy is not arrogant nor smug in the slightest. Though he does project confidence openly and wherever he goes, he does so knowing the limit of his ability, skill, and experience. He's a natural-born leader, and being in a Military position of power, showing weaknesses and hesitation would put himself and his men in danger. Roy has no problem in admitting he lacks skill for certain duties and tasks, but takes immense pride in knowing that he's an excellent and proficient alchemist, gets the job done well most of the time. He understands and appreciated the danger in situations and knows how to act accordingly, (whether retreating, attacking, or some other unforeseen event). Ironically, Roy has an inner self-loathing habit, which is mostly a result due to his experiences during the Ishval/Ishbal Rebellion.
Though Roy may appear cold and austere to outsiders, he is candid and warm with the people he cares about, and never hesitates to offer his help if a situation calls for it. If someone he cares for is in danger (especially if it's because of him), he will go to whatever extent necessary to protect them, and will not stop worrying about them until they are safe. Part of Roy's admirable character (and charm) is that not only is he passionate about his goals/ideals, but he is also equally as passionate about taking care of whoever may need it/those he cares for.
Further misconceptions regard Roy's morals. Again, we feel this stems from his character portrayal in the anime, more so that from his manga character. Roy is not morally "neutral" or even remotely close to it. If anything we would characterize his moral standing as "chaotic good." Roy's goals were set before he encountered the Elric brothers, and Roy has no trouble distinguishing what's "bad" from "good." One reason he forged such goals, is due to his steadfast commitment to benevolence and a greater "good". Also, though his convictions are strong and he has a steadfast resolution to attain his goal, he will not take innocent lives to reach it (this is not to say, however, that he won't derivate from the path of "socially acceptable" to get there). Roy will use any means necessary to reach his goals, so long as innocents will not become a casualty.
Roy is often labeled as a lazy bastard, but again, a careful read through the manga will disprove such claims. Roy is absolutely a procrastinater (thus tending to leave paperwork to the last minute), but procrastination is hardly proof of not doing his job. Many procrastinaters are quite skillful at their jobs. Roy is greatly valued by his superiors in East City (the ones who don't get irritated/jealous by his fast ascent through the Military ranks), and was assigned a massive amount of work due to his (and his team's) efficiency. Also, one can not get so high up the military that young (and quickly) without working hard and being good at his work, by sheer laziness.
Lastly, the whole "he's obsessed about mini skirts" thing, is a humorous tidbit that was done as an extra manga in the extras section. Asides from in the extra shorts, Roy makes no reference to a personal military harem of short skirt wearing women to serve under him. Though he frequently mentions going on dates throughout the story, we have yet to actually see/here one of such dates. Though, thrown in as a humorous side of the Flame-Colonel, neither of the WebMasters would say such pervy characteristics would even remotely describe the Colonel. Besides, who hasn't succumb to slightly pervy thoughts every once in awhile? After all, the Flame-Colonel is only human.
Roy Mustang: Ideals
One of the most defining parts of Roy as a character are his ideals. Out of the entire Fullmetal Alchemist cast, he is by far the most idealistic. Part of what makes him so interesting is that his ideals evolve as the manga progresses. Such evolution comes from his changing views towards the world, and his never-ending adjustment of his beliefs due to his own experiences. Roy originally learned alchemy so that he would be able to protect all and everyone he could. He joined the Military in order to make a difference and help build a society in which he was able to protect the people, and allow no hardship, war, or sorrow to befall them. After witnessing the atrocities of the Ishval Rebellion, Roy vowed to become the next Fuhrer in order set right what the Military has caused, and end the war and hatred. this concept serves as the basis for Roy's ideals. It is a wonderful and even beautiful dream, but naïve, nonetheless. Unfortunately, early on, Roy failed to note that the world is not as simplistic as he makes it out to be, or that all people share in such an idealist vision as he does. Rather abruptly, he soon finds himself in the middle of a corrupt, cut-throat, and self-interested world, one in which people live for the sole purpose of their own self-interested ambitions, and a King who has no regard for the well-being or happiness of his people.
Despite such a disruption to his vision, Roy refuses to give up on his goals. Even after going through the horrifying experience of the Ishval Rebellion, where he was forced to participate first-hand in a massacre, he refuses to give up on his view of society, or on his goals to change his country. Though not the path originally intended, Roy realizes that is is still possible to change how the Military operates, and that as Fuhrer, he can make that difference. As a result, he does not have the option of backing down, or running away from what he considers his duty. Instead, he comes up with a different approach--one that is a more realistic and pragmatic way of making the world a better place. Realizing that he is only one man, and that he cannot protect everyone and all, he vows to protect the few that he can, as well as protect the ideals most important to him. By protecting his ideals, and those he is able to protect, those he protects will in turn protect their own ideals and anyone they can protect, so that the cycle continues and everyone continues to protect whom they can until the tiniest of creatures has the protection from someone more powerful than them. To put it more simply: protect anyone you can (those under you, those smaller than you), in turn those smaller than you protect who they can, until the smallest/most defenseless person/creature/life is protected.
Mustang is ale to leave Ishval with his strengthened resolve in mind, and with the tenacious desire to overthrow Fuhrer King Bradley, begins to calculate his move (though he is aware of the fact that he can't fulfill his ambition alone). His best friend, Maes Hughes gives him the final push as well as the reassurance that he could/will make it to the top, and so Roy entrusts Riza Hawkeye with the duty of looking over him, not only for the sake of his security, but also so he wouldn't betray himself and stray from his path. If he was to ever stray from his path, he orders Riza to shoot and kill him (talk about conviction). Finally, Roy makes sure to find some comrades who would not only believe in him, but whom he could trust his life to (and they in exchange would do the same).
Roy is unable to forget his experiences and the pain he, and the people around him, had to endure. He uses such experiences and empathy to refine his ideals until they became something pragmatic enough to accomplish. Roy creates new hope for the future, one in which Roy and the people supporting him, believe in so fervently, that they are all ready to defend it, no matter what.