I don't own Sherlock, the BBC does.
Obsession.
Moriarty had noticed Sherlock when the latter had foiled two of his plans. Moriarty had always kept himself in the shadows, but he couldn't help but feel impressed; his plans were airtight, and yet this ' amateur' detective had foiled those plans after a few mere moments at the crime scene.
Jim had been in the Consulting criminal business for a few years now, okay granted he was the only one in the world, but he was doing his best to gather contacts and informants, and he had one in the police force.
It didn't take him long to find out from one of his police informers - young girl, stupid, brain like a sponge - about the new ' consulting ' detective. Sherlock Holmes.
Moriarty had been intrigued at once, and started visiting his website, expecting to read about crap only to find THE SCIENCE OF DEDUCTION to be well construed, but Moriarty understood it all because he used the same basic observational skills himself, he could tell when one of his workers was lying to him, what someone had done the night before and so on.
Jeff Hope was owed a favour by Moriarty, who'd done some small leg work for the consulting criminal in the past. Moriarty had a weakness for generosity, a weakness that saw him try and persuade Sherlock Holmes not to interfere, but in the case of Jeff Hope it was a weakness that turned the whole thing into a test.
Sherlock was proving to be more of a problem than Jim had wanted. Many times had one of Jim's underlings, people who piggy backed emails and mobile calls to reach him, and on each occasion where Jim expected to hear of success, he found only failure.
Sherlock was becoming nothing more than an overgrown boyscout, and Moriarty hated those since he couldn't do it because they were sissies and dogooders.
Hope had been dying, and Moriarty had quietly but quickly learnt about it. Moriarty had him brought to the Room, where Moriarty could speak to him without being seen. Jim had never let anyone see him for real in keeping with his policy of no direct contact, but Hope knew how dangerous Moriarty was. The aging crook accepted the job offer for killing as many people as he could using poison, in exchance money would go into a trust fund.
Some might ask what was the motivation, the answer was obvious. Jim Moriarty wanted to up the game he wanted to make with Sherlock, he wanted to show the detective there was an underlying element in the underworld.
It was a test. And what a test, with such bait. How could Sherlock resist the question of a serial killer using poison to kill victims using self inflicted means.
For the first couple of murders Moriarty watched patiently as the police searched for conceiveable leads, he'd watched the rather pointless press conference with a critical eye, shaking his head from time to time.
One thing caught his attention, those text messages saying Wrong!
Sherlock was watching, Sherlock was investigating. For Jim, this was breaking out the champagne time. The bait had worked!
Sherlock didn't disappoint him.
Jim had Sherlock watched from time to time, not often because the detective might detect it, but he knew when Sherlock invited former army doctor John Watson to bunk in with him, and the doctor seemed to connect with Sherlock easier than he had with the clueless police.
Sherlock had found the briefcase. Jim had been rather disappointed by that; Jeff Hope's brain had been clouded so he hadn't realised his mistake until too late. If Moriarty had wanted to remain hidden, he would've told Hope to dump all possessions with the dead, and be on his way.
Hope died, and Moriarty had no idea if he'd been compromised, but bleeding on the floor with a bullet in the shoulder was the perfect way of knowing if someone wanted answers.
Moriarty didn't know, and frankly didn't care.
Although Sherlock was proving to be Moriarty's intellectual equal - almost - he was still a problem, and Moriarty was beginning to lose sleep because he didn't want his phone to go off telling him about another disappointment.
Moriarty had been furious when the Tong operation failed and the jade lotus hairpin was lost, and he'd made sure she paid for it.
Boredom.
Moriarty hated being bored. So he established a plan to expose and unravel some of his plans. The Carl Powers case of Sherlocks, unsolved of course, had proved to be the most interesting point in the whole thing.
Cutting loose the fake painting, the betrayal of Janus, the murder of Connie Prince had been insignificant to the long term, but the decision for those particular plans hadn't been taken lightly. Moriarty had other plans and schemes, some of them planned for years, but those were the ones he'd deemed the most necessary.
Also it gave him the chance to finally meet Sherlock. He'd gotten together with Molly Hooper, and he'd found her sweet, but she wasn't his type, and he loved talking about Sherlock. Like the meek lamb he was pretending to be, Jim had acted all awestruck, only to be disappointed when Sherlock had ignored him.
For someone who had skills in deduction that went far beyond the lesser people, Sherlock Holmes was far too obtuse to see what was around him. That pleased Moriarty to an extent, it proved him to be human.
Oh, the surprise Sherlock had had when he'd revealed himself. He hadn't shown it, too egotistical of him to show surprise, but it was there. Watson certainly hadn't hid his surprise when he'd discovered Jim from ITs real identity. Moriarty had given Sherlock the opportunity to stop prying, to walk free but he'd known Sherlock simply wouldn't take it. He would continue prying till one of them was dead or buried.
Moriarty had been given the choice to see Watson and Holmes die that night, only for Irene Adler to phone and ruin it.
On one level, he was grateful. He had something special planned for Sherlock, something so special it would fall from a great height.
He'd been captured by Mycroft Holmes, Sherlocks government brother. Moriarty hadn't liked him, too smooth, condescending to the point of arrogance, and he'd wanted information.
Moriarty didn't care much about himself, he knew the British government wouldn't want torture, so he was safe to an extent. He told them nothing about his methods, but then Mycroft gave him something precious; information about Sherlock. In return Moriarty gave them all kinds of crap, some of it not even real, then he was released.
He was finally ready to deal with Sherlock, and who would've thought Mycroft Holmes would be the one to provide him with his weapons?