Warnings: SPOILERS! Seriously, if you haven't seen His Last Vow, don't read this!
Also, hints of pre-slash :)

Jim Moriarty.

As much as Sherlock simply did not understand normal people or their odd emotions, he was well aware of the fact that the little thrill he got on hearing that name drop from Mycroft's lips once more was a bit not good. Moriarty had been – still was, it seemed – the single greatest nemesis that Sherlock had ever had to face, somehow managing to surpass even Mycroft. Being hap- interested by his return was definitely not an appropriate reaction, and that was something that even his infinitely more sociopathic elder brother would agree too.

That didn't change the fact that the first thing that Sherlock had thought when he heard that the consulting criminal had seemingly returned was, "Well, at least this won't be boring."

Honestly, it wasn't that he was devoid of interesting cases or things to do with his time. He had his experiments, and ever since Mary had entered his and John's lives, it seemed like the puzzling cases had tripled.

And then there was Mary.

In another time, she would have been the perfect nemesis for him – ruthless, but still possessed of a heart. So very similar to him – he could understand why John had fallen in love with her.

But in the here and now, she was an ally, and more than that, she was one of the few people he felt comfortable enough to call friend. Which was good – he would even go so far as to say it was wonderful – but the fact that remained that it left him lacking an adequate rival.

Magnusson hadn't counted. Unlike Moriarty, he had been so devastatingly simple, for all of his effectiveness. Besides, unlike Moriarty, he wasn't one who liked to play the game – instead, he was so much more direct. So much cruder, as Moriarty would have said.

Of all the foes he had ever faced, Magnusson was perhaps the one person who had truly inspired hatred in him. Even Moriarty, he had only despised during those moments on the roof – as long as those close to him remained out of danger, he had perfectly happy to continue with the game, selfish as it may have been.

But Magnusson had not only turned his gaze on one of the few people he truly cared about, he also made his wealth by exploiting the things that made a person unique. Moriarty would have used them, no doubt – but he would have treasured them all the same. In Magnusson's world, the only way to be perfect to be horrifically, boringly same.

He had killed the man for Mary's sake, true – but at the same time, he had also killed him for himself.

And while he had regretted leaving, a part of him had delighted in it at the same time. John and Mary were lovely people, perhaps the only partially normal human beings who would ever understand him – but they had each other, and as soon as the child was born, he would take a backseat in their lives.

It was the way it should be – Sherlock would never have wanted it to be different – but the thought of it still hurt.

So, MI5. At least he would be doing something, even if it meant his certain death.

And then – Mycroft's glorious phone call.

He shouldn't have been pleased at prospect of dealing with Jim Moriarty again. If Mycroft ever realised the depth of his interest, he would never let him see the outside of an institution again.

But Moriarty was interesting, and Sherlock knew him in ways no one else ever could. He had no doubt that the man had learnt better than to ever try and target those closest to Sherlock again, or at least, not in the way he had done on the rooftop. Not when there only one visible option out.

Future threats would mean bombs strapped to the chests, not snipers with trigger happy fingers.

In many ways, Sherlock needed Jim Moriarty just as much as he needed John, or Mrs Hudson and Lestrade, Mary and Molly, Mycroft and Mummy and Daddy. In a twisted, crazy way, Moriarty was part of him.

So he was – happy wasn't the word. Interested perhaps, which said so much more than mere happiness in a person like him.

The game, after all, was finally back on.

After the ending of His Last Vow, I really couldn't resist, even though I'm a Johnlock shipper at heart :D
I hope you guys liked it! As always, please don't forget to drop a review on your way out :)