Moriartys for the movie-minded.

There's a trope you might recognize, if you've seen enough superhero movies.

Given the roughly two-hour time limit to tell a story, and wanting to contain all the details of that story in a single package, movie makers often roll the villain's origin story into that of the hero. Villains who weren't around at all when the hero came to be suddenly are right there, getting hit with cosmic rays alongside the hero, shooting his parents, traveling along from a planet he was supposed to be the lone survivor of . . . at least for a little while. Hollywood is almost past its "gotta have an origin story" phase, so maybe this trope shall pass. But not before it got its hooks in Sherlock Holmes.

As with many things, Holmes was a bit ahead of the crowd. The most well-known tale of him getting his powers from the same incident that created his "arch-nemesis" was The Seven-Per-Cent Solution. Nicholas Meyer, being a book guy and a movie guy, rolled his Moriarty, Holmes's drive to solve crime, and the drug addiction into one tidy little package, in book and film. Given his plot, it seemed kind of natural.

But then we move on to Barry Levinson's Young Sherlock Holmes. Not satisfied with merely bringing Holmes and Watson together at a much earlier age, the Chris Columbus screenplay dragged Moriarty in as their school math instructor. And thus, all their origins happened together.

The biggest of the 221B Baker Street films, Guy Ritchie's Sherlock Holmes, dodged that bullet and had Moriarty sneaking out of the London woodwork like he's supposed to, but the Asylum film of the same title, affectionately known as "Sherlock Holmes and Dinosaurs" doubled down on the idea.

Forget Moriarty, forget Mycroft Holmes, forget any Scotland Yarders who were not as smart as Sherlock . . . mash all of those ideas together and you get Asylum's Thorpe Holmes . . . an arch-enemy for Sherlock Holmes who came from the same birth canal as the great detective, combining Moriarty, Mycroft, and Scotland Yard with a robotics genius.

Is Sherlock Holmes a superhero, whose origin needs to create an arch-villain of equal or greater power? Well, we do speak of his "powers." And he is a substantial level above the "mere mortals" of the police force and his room-mate, so one could see why some might put him in that category.

But when you come right down to it, Sherlock Holmes was a detective, James Moriarty was a criminal, and neither of those requires a rare and fantastic lightning strike of an origin to explain mere genius. We know genius happens, in all sorts of professions. Why not in detection and crime?

But sometimes, well, you know Sherlock . . . he has to do everything once.