To John H. Watson, he was always the dictator.
The only one the good doctor ever wrote of, "the most lewd and bloodthirsty tyrant that had ever governed any country with a pretence to civilization," the man they called the Tiger of San Pedro.
Watson lived in a pre-Hitler era, when people didn't have that over-used tag to throw on a purely evil tyrant. It's interesting that Watson does not compare Don Murillo, the aforementioned Tiger, to any world leader of the past. But as a writer, he was still able to describe hime well enough.
"Strong, fearless, and energetic, he had sufficient virtue to enable him to impose his odious vices upon a cowering people for ten or twelve years."
Interesting statement that -- even the sleaziest of bullies must have something for someone to admire, as no many can take leadership of a country without the cooperation of somebody else in that country. Some army must follow him. Some key people must find some profit in him. One man is just one man. And with no support from anyone else, any one man will fail.
And eventually, after more than a decade as "a terror through all Central America," there was what Watson describes as "a universal rising against him." Armies quit following. Key people found no more profit in him.
Dictators eventually run their course, whether they're cast as "benevolent" or "blood-thirsty." We haven't developed immortality as yet, and even when we do, no one thing remains consistently popular or functional forever. And any one man can inevitably be replaced by some other man (or woman). If a dictator like Don Murillo is bright enough to see what's in the cards, he gathers his resources and escapes while he still has the power to pull it off. But even then, one has to be careful just how many people are looking to get their revenge or justice for the abuses of power.
It's funny how we often see dictators the way Miss Burnet suggested that Sherlock Holmes saw Don Murillo: "To you they are like crimes committed in some other planet." (Side note: Even though it may seem odd that a Victorian governess thought about life on other planets, people have had that thought going back at least to ancient Greece, almost considering other worlds the way we thing of parallel universes today.) In other words, "it can't happen here."
And maybe it won't in our lifetimes, though one could see how it might as barons of politic and corporation work to ensure their power. But even in the Sherlockian Canon, the rise and fall of Don Murillo, with that fun title of "the Tiger of San Pedro," gives us a vision of how that tends to work out.
And why we like honest fellows like John H. Watson so much better when all is said and done. The ones who remember what a dictator was like when they hear of him.