This was written for my entertainment and because I had to get it out of my head. Seriously, the moment I get jittery from NOT writing the scenes in my head I know it's time, consequences be damned.

This follows in no way anything of canon, aside from mentioning a few tidbits here or there, mostly season one and maybe a little of season two. I stopped watching the show when it became too multiversey for me. Season three was the last one. Same for Legends. They killed off Snart. Damn them!

So… don't expect a lot of canon stuff. I took what I found interesting, then added my own, and then I ran off with it, never looking back. And when I say run, I mean really fast, really hard.

Not to mention that it's so very much AU due to the whole Sentinel and Guide take. As usual, this isn't the conventional Sentinel-Guide theme. I like to play with that concept my own way. Those who read my other fics know what that means... Hope some of you enjoy this!

Science had determined that about 3.15 % of the world's population were born with a slightly different genetic code that gave them an edge compared to others. Nothing as extreme as shapeshifting or comic book mutant powers. No, it was more subtle and yet had an impact on those where the genetic change was triggered from latently passive to suddenly active or even hyperactive.

One to five enhanced senses were the most common change. Sight, hearing, taste, smell and touch. It could show early or late, strongly or just a little over average, and there was no determining factor when a hypersense manifested. Some attested it to a sudden trauma, physical or emotional, in the person's life. In others it just happened without such trauma ever present.

Societies called those with hypersenses Sentinels, mostly because a large percentage of them had a very pronounced protective streak.

Then there were those with a more spiritual power, a form of empathy, but never telepathy. In some it was almost precognition. They connected to Sentinels on a very complicated, not yet completely explainable level. Some would only find one perfect match. Others were more universal.

Societies called them Guides, able to aid those with hyperactive senses to protect them from the backlash of their unique ability.

Not every Sentinel needed a permanent Guide. Sometimes they only took the edge off, like first aid, never connecting on a deeper level. Some Sentinels chose one Guide, and only the one. Those were usually soldiers, officers of the law, or ones who worked in security. A few jaded ones never trusted a Guide on such an intimate, incredibly personal level.

Leonard Snart hadn't been born a criminal. He hadn't come into this world as a bad person, but he had quickly started to go down the wrong path, which was in no small part thanks to some not so stellar parental upbringing. His father had made sure to bring out all the bad in him, to use him for criminal purposes, and to shape his son's life the way he saw fit and profitable.

Forcefully. Beating it into him to be the best at being bad. To use his brain. It was one talent his parent had rather quickly discovered and exploited: Leonard's penchant for making plans right down to the second. The way he cased a job, how he calculated the odds, how he pulled it off, was almost a signature now.

Who was he kidding? It was a signature. The detailed planning of a master tactician. The time he took before doing a job. How he selected each heist, never getting cocky or taking on anything that was way over his head. He chose the job, the crew, the time and the date. And he demanded nothing but complete obedience to his rules.

"We don't shoot cops or guards, unless it's the only way."

If there was one thing that could be said about Snart it was that he wasn't cruel and merciless. He didn't torture. He didn't take lives for the fun of it, but he accepted the collateral. His plans were efficient, his timing perfect, and he was known not to suffer fools lightly.

Yes, he had killed, but never preplanned, never an assassination.

Despite his father's hopes, his son hadn't developed any hyperactive senses. He wasn't exceptionally good at hearing a lock click. He had no enhanced sight or touch. Lewis Snart would have had no use for taste or smell, so that was never tested. Touch, sight, hearing, that was what a top-notch thief needed.

Leonard had none of that.

Despite not showing any signs, his father had dragged his teenaged son to some more shady doctors to test him for hyperactive senses, or even some latent psychic ability. If he wasn't a Sentinel, maybe he had Guide abilities. Some of them were empathically strong enough to charm others into doing whatever they wanted. Very proficient con-men with an edge.

The only slight spike in the test happened when he engaged his mind to case a room, calculate the odds and start the countdown. That's when a switch was flipped and he saw the world in a different way. Time meant something to him. He used his grasp of time and relative space, saw all the angles and possibilities, and he could almost render the whole scene in his head. He was briefly immersed in a world that was real and then again not. He could walk through a scene and change it to see if the plan was viable. Give him video feeds, pictures, blueprints, or maybe let him walk through the room, and he would be able to call upon the image even days later.

"Something's there," the scientist had told Snart senior. "It doesn't ping on the known scales. He's definitely not a Sentinel and he has no empathic abilities. His IQ is remarkable, which might explain his awareness of time and space. But that's about it."

Lewis Snart hadn't been pleased to hear that and he had taken his anger out on the hapless thirteen year-old.

Len hadn't cared about being a Sentinel. He hadn't cared about anything but trying to be the best he could be, please his father, but nothing had ever been enough. Not his perfectly, carefully planned heists, not his loot, nothing.

His parent had finally ended up behind bars once more, though it wouldn't be the last time. Lewis had frequently been in jail for extended periods at a time for armed robbery, aggravated assault and assault with a deadly weapon. This time it had been a longer sentence, one that wouldn't see him out of Iron Heights for at least a decade.

Len had left this part of his life behind, while using a huge chunk of that old life to start his own criminal career. Free of his father's influence.

He lived an unapologetic criminal lifestyle. He was ruthless. He was the best for any heist.

It was a Sentinel of all people who told him that he was apparently a blind spot for her, and especially for her latently empathic partner. Mina was a thief like him, but with heightened Sight and Touch, which was quite helpful in her line of work. Patrick, her partner in so many ways, acted as a Guide. Mina had watched him like a hawk as he had cased a room, picked out the weak spots, given her a time frame and told her what to do step by step, second by second.

"You've got some kind of talent, kiddo."

He had been nineteen at the time.

"Not sure what you are, but you feel… weird. Shielded."

"I'm not a Guide," he had growled at her.

It had gotten him a wry smile from Patrick. "Yeah, you're not. Definitely not like the ones I've met before. Kind of special. Got tested?"

He had glared at them some more, which had had her laugh.

"Do you even know how to drop your shields?"

"There are no shields. Now stay out of my business."

There had been doubt, but in the end the pair had dropped it. Len didn't follow up on their suspicion that he was shielded, that part of him was very much hidden from those with a slight edge.

So he had an instinctual defense he wasn't aware of and he didn't respond to anyone's empathic probing. Good. Just another edge, a means to a criminal end. If he could slip by a Sentinel or a Guide as he worked a job, all the better.

That was until he met the red streak called The Flash.

Well, a red blur that had thwarted his perfect plan to rob an armored car, throwing a very big wrench into things.

But Snart was fascinated by the guy. He wanted to know more about the protector of Central City. It was a fascination that bordered on obsession and which he tried to rationalize again and again. Central City was his hunting ground, his territory, and he had driven off other criminals with force, if necessary. It was his city to poach and plunder, and also to keep the unsavory elements from turning it into some powder keg of rival gangs and wanna-be crime lords.

As Captain Cold and with the cold gun, he had another argument to keep everyone in check and run his heists effectively. Especially with Mick Rory at his side, part of a new gang, though Rory was somewhat of a hot-tempered, loose canon. He had known the other man for a long time, actually since before cutting ties with his father and making his own way. Len had been fourteen at the time, still a too easy target, and Mick had been the one to chase away the bullies.

Snart hadn't know it at the time, but Rory had already been triggered by nothing less than fire and flames, his senses sharp but not overwhelming, and he had never looked for anyone to help guide him. He embraced the spikes, lost himself in sight, sound and even touch of the fire that had given him his abilities.

Len knew the demons that resided in that dark, dark place of Mick's soul. He also knew that Mick Rory was one of those unlucky bastards whose senses were once again swallowed by a more personal trauma. It had numbed him, made him unreceptive. He was neutralized, so to speak, and because of that, Sentinels and Guides were just as blind to him. He had been one of them once, but the heat of the fire and the darkness afterwards had swallowed that.

Still, Rory was the best weapon to have on his side, a known fact, not a variable.

Their jobs also had The Flash chase him, make it so much more fun and entertaining, and Len's brain kept cycling through many plans and calculated all the possibilities, making it an exhilarating job each and every time. He felt more alive when it came such encounters. Adrenaline spiked, everything was crystal clear and sharp, and despite The Flash's speed, Captain Cold could keep up with him.

It became a game.

Even when he discovered the guy's true identity.

Even when he wondered how a kid who looked like was still given curfew and a regular bedtime by his dad could do what this guy did. He worked a regular job, at the local police department of all places, and ran around thwarting new meta human crimes on top of helping the police with very much mundane stuff.

Barry Allen became an obsession.

A not so bad on the eyes obsession, very nice to look at, and something inside him hummed with pleasure.

This controlled wildness was… attractive. The electricity, the lightning… The Flash was a coiled spring, ready to be unleashed. He was still growing into his power and Snart actually enjoyed pushing him to his limits. Testing him more and more. Speed, coordination, sense of space and time. Len had never reacted to someone like he did to Allen. It wasn't purely lust or hunger. It was deeper. It was something primal and yet still controlled.

Snart had dug deep, had unearthed what he could find about the young CSI. It was half instinctual since The Flash was part of his territory. Another part was simply curious about this man because…

Yeah, because.

Len was drawn to him and it was slightly bothersome.

First rule of business: always protect yourself.

Well, that rule had gone out the window fast.

He never pinged The Flash as anything but a do-gooder with a way too soft heart, but a quick, sharp mind. Hit by lightning in a lab full of chemicals, a meta human, but that was all he was.

So why did he bother with him? Why did he always come back? It wasn't just the handsome face and the nice to look at body. It wasn't the fun, the banter, the adrenaline.

It was something else. It was something deep inside, something that hadn't been heard since his childhood. It was underneath a metric ton of shields and walls, but it was listening to something only it could hear.

The return of his father had driven home the fact that Len had changed. He wasn't a child anymore. He wasn't an easily manipulated teenager either. He wasn't Leonard. Everything about him had changed.

But he had to go along with his father's demands to keep Lisa alive.

Seeing Barry getting shot had almost had him pull his gun on Lewis and be done with it. If not for Lisa. She had been the one he had to protect, though that instinct had been at terrible war with the one to also keep Barry safe.

The Flash.

Snart had almost laughed when he had realized Scarlet was alive, that he had not so much as a scratch on him, and he felt no remorse when he ended his father's wretched existence.

"There's good in you," Barry had told him, eyes intense, refusing to let him look away. "There is a part in you that wants to be more than just a mere criminal."

Prison hadn't been able to hold him long.

When Captain Cold and Heat Wave had joined the Waverider and the Legends, Snart hadn't missed anything from his old life. Except Scarlet. It wasn't a sense of loss or like a connection had been severed. It was just that personal thrill that couldn't be replaced by whatever time adventure they had.

He was a misfit among misfits. He was a supervillain who wasn't bad to the bone at all.

And then he died.

Well, bad days happened.

Really, calling it dying was a bit of an exaggeration, because he had disappeared into the unleashed Time Stream and that was that. Everything was suddenly a total nothing, except for that power everywhere. Out of the nothing myriads of strings burst forward, twisting and waving, melting together or unravelling into oblivion.

Time was… not something any living soul could describe in words. Time wasn't anything anyone could really understand. And Time was somehow more than a concept. It was Something. It felt like a presence, like a mind and yet not sentient like another human being. Or alien being. There was no word in any language that fit what Len encountered as he supposedly died.

Time found a receptive mind in him, able to process more of it than many. It had been his knack for all his life. Time was no stranger, the math easy. He liked time and he understood it. So when he ended up inside the Time Stream, he wasn't torn apart, turned into single molecules to disperse. He was energy for a while. Just existing.

Time had become unmoored, he was told, but it was healing. It was focused on him as he held the key to its recovery. The Oculus had been a shackle. Now, after it had been torn apart, all those time lines had become undone, dissolving, reforming, being eaten up or thrown together, healing Time to be what it had been since, well, the beginning of time.

Len was the focus, the conduit, and he curiously watched it all unfold. With no sense of passing time, only Time itself. He watched the different events in all the time lines, some happy, some sad, and most he forgot afterwards.

He wouldn't say they became friends, but he was left with the impression that while it wasn't truly sentient, it was really Something. Time used him, his innate ability to streamline wildness, give it a sense of control, quiet down the erratic spike. He hadn't known he could do this.

Time didn't really talk to him, but it made him understand that yes, he could. Not perfectly, though. Then it put him back together and he was back, just weeks after he had left with the Waverider for the first time.

It was a bit jarring, really.

Especially since Mick and he had started out as a team and now there was only Snart left. Despite all their ups and downs, the betrayal, the darkness, the loss and the reconciliation, Len still thought of Mick as more than a tool. Mick had been the first guy to stand up for him, to have his back, and no matter what had happened later on, he knew where it came from. He knew the dark place, had seen the grief and pain, had lived through those agonizing months as Rory healed from the burns that had left the extensive scars.

Len went back into his old life, with a few small changes.

Okay, maybe some rather big changes.

For one, he ditched everything and anything of that old life. Including all his hideouts. His accounts were still where he remembered them. Well, only a month had passed since he had started his Legendary adventure, so he shouldn't be surprised.

Cold also no longer had a team with him. Mick was wherever or whenever, Lisa had skipped town and was hunting in greener pastures, and the Rogues had either left for places where The Flash wasn't around to stop them or they had ended up behind meta-resistant bars.

So yep, he was working alone, did a few jobs for hire, and always looked forward to his little trysts with The Flash.

Fun times.

Until that fateful night when a new meta got the better of The Flash.