Professor Moriarty: Sir Arthur Conan Doyle's Genius Villain....

 

Moriarty is highly ruthless, shown by his steadfast vow to Sherlock Holmes that "if you are clever enough to bring destruction upon me, rest assured that I shall do as much to you".^[8] Moriarty is categorized by Holmes as an extremely powerful criminal mastermind adept at committing any atrocity to perfection without losing any sleep over it. It is stated in "The Final Problem" that Moriarty does not directly participate in the activities he plans, but only orchestrates the events or provides the plans that will lead to a successful crime. What makes Moriarty so dangerous is his extremely cunning intellect:

He is a man of good birth and excellent education, endowed by nature with a phenomenal mathematical faculty. But the man had hereditary tendencies of the most diabolical kind. A criminal strain ran in his blood, which, instead of being modified, was increased and rendered infinitely more dangerous by his extraordinary mental powers. He is the Napoleon of crime, Watson. He is the organizer of half that is evil and of nearly all that is undetected in this great city...

— Holmes, "The Final Problem"

Holmes echoes and expounds this sentiment in The Valley of Fear, stating:

The greatest schemer of all time, the organizer of every devilry, the controlling brain of the underworld, a brain which might have made or marred the destiny of nations—that's the man! But so aloof is he from general suspicion, so immune from criticism, so admirable in his management and self-effacement, that for those very words that you have uttered he could hail you to a court and emerge with your year's pension as a solatium for his wounded character. Foulmouthed doctor and slandered professor—such would be your respective roles! That's genius, Watson.

— Holmes, The Valley of Fear

Moriarty respects Holmes's intelligence, stating: "It has been an intellectual treat for me to see the manner in which you [Holmes] have grappled with this case." Nevertheless, he makes numerous attempts upon Holmes's life through his agents. He shows a fiery disposition, becoming enraged when his plans are thwarted, resulting in his being placed "in positive danger of losing my liberty". While personally pursuing Holmes at a train station, he furiously elbows aside passengers, heedless of whether this draws attention to himself.

Doyle's original motive in creating Moriarty was evidently his intention to kill Holmes off. "The Final Problem" was intended to be exactly what its title says; Doyle sought to sweeten the pill by letting Holmes go in a blaze of glory, having rid the world of a criminal so powerful and dangerous that any further task would be trivial in comparison (as Holmes says in the story itself). Eventually, however, public pressure and financial troubles impelled Doyle to bring Holmes back. While Doyle conceded to revealing that Holmes did not die during "The Final Problem" (as Watson mistakenly concludes), he chose not to undo Moriarty's death in a similar fashion. For this reason, the later novel The Valley of Fear features Moriarty as an active villain but is specified to take place before the events of "The Final Problem".