Summary: Cisco had thought that future!Barry was gone until he walked into his apartment that evening to find the speedster with the white emblem sitting on his couch snacking on fries from Big Belly Burger and a faintly guilty expression on his face as he looked up.

(Or, Cisco's day won't stop circling back to Hartley Rathaway and time travel, both of which induce headaches merely by existing.)

Notes: AU for "The Sound and The Fury" but also "Flash Back". Barry traveling back in time to stop Hartley was always how it happened and the second Time Wraith doesn't show up until Barry is back in the Speed Force, so Barry's return to the future in "Flash Back" happens differently. Also, no Ferris Air snafu because in this 'verse the pipeline cells were only ever temporary measures and the metas all ended up at Iron Heights after at most a week in STAR Labs while having specialized containment procedures created for them. Why? Because ethics. (Though Wells was sold on it because keeping metas locked up drained resources better spent on Barry.)

This one's been up on Ao3 for a long while now, but I didn't realize it wasn't here until I wrote a sequel for it for Hartmon Fest.

Part 1 in the Pied Piper's Army of Rats

(Predestination) Paradox

It had been a long day and, as Cisco fumbled for the key to his apartment's front door, he was mentally reviewing where he'd left his aspirin – there was Tylenol somewhere in his bathroom, but the question was whether it was sitting out on the counter or he'd remembered to actually put it away in the medicine cabinet the last time he'd used it.

The headache had a name – or at least a cause, anyway – and that name was Hartley Rathaway. Oh, sure, the bending his brain around the fact that time travel was real, nearly getting killed by a Time Wraith, and trying to keep straight which version of Barry he was talking to at any given moment probably contributed to the headache, but mostly it was all Hartley's fault. Because Hartley had caused Cisco's day to start with the news that Wells had been attacked at home, where he should have been safe. Sure, Wells was fine, but that wasn't the point. Then Hartley attacked the Rathaway corp building, blowing out the windows and generally causing as big of a fuss as possible while staying within the realm of vandalism. All to get Barry's attention in order to have them bring him into STAR Labs so that he could use his exploding hearing aids (Cisco still didn't understand the level of desperation Hartley had to sunk to in order to be willing to have explosives in his ears… that was just mind boggling) and steal… something. Future Barry hadn't been very forthcoming on Hartley's endgame, just his methods.

Everything pretty much looped back to Hartley, though. Time travel? Future Barry keeps Hartley's plans from succeeding. Time Wraith? Cisco and Caitlin get stuck in the same pipeline cell as Hartley trying to escape from it and wind up having to hand over the Piper gloves to let that smug asshole save their lives. (Which Cisco had immediately thanked him for because Cisco would never let it be said he was ungrateful even when the 'hero' of the hour was a professional jackass. Dude might be a Harry Potter fan, but he was definitely Draco Malfoy on any 'which character are you' quiz.) Worse, they were going to have to actually work with Hartley instead of coming up with a containment method for him before handing him off to Iron Heights like they'd done with all the other metas they'd caught. (In this case, just taking his gloves away and pinning a note to his jacket saying 'likes explosive hearing aids, but does in fact need constant sound dampening' would probably suffice.) All because Hartley had the expertise they needed to develop a device capable of driving off Time Wraiths.

In fact, the only thing that didn't loop back to Hartley was Cisco's difficulty keeping straight which Barry was which. Thankfully the suit emblems were different colors and, wow, the white on the future emblem just popped. Made the lightning bolt stick out so much nicer than the current red background and, really, Cisco was already planning on replacing the emblem the next time Barry wrecked it with one that matched the future aesthetic. (Seriously, though, did Barry think those things grew on trees or something? He was going to have to bring that up with Barry at some point.)

With the key finally in the lock, Cisco undid the deadbolt and pushed open the door. He walked in, glancing over at the kitchen and trying to decide if he wanted to do chicken and pasta because it would be easy to make or if he wanted to just be lazy and order something, when the scent of Big Belly Burger hit his nose.

Cisco had already given the front door enough of a shove for it to swing firmly shut behind him and the sound caused the interloper on Cisco's couch – an interloper eating Big Belly Burger – to flinch and then look up at Cisco almost guiltily.

This interloper being one Barry Allen clad in a bright red Flash suit with a white emblem.

"Aren't you supposed to have gone back to the future?" Cisco asked, walking over to his stash of delivery menus. Because, yeah, there was no way he was going to have the energy to cook after this.

"I know I said I would and I made it look like I did, but… um… there was actually one last thing I needed to do here first. Something you told me to do. Future you, I mean, not current you because obviously… well." Barry paused and then poked awkwardly at the remains of his fries. "Am I confusing you? Because I might be confusing myself."

"I told you to come here and confuse me?" Cisco asked dubiously, giving future Barry his 'stop speaking nonsense' look that… didn't really work all that well, if Cisco were being honest with himself. Picking a menu at random, Cisco dropped it on the kitchen counter and closed the drawer with the rest of the menus inside.

"No. No that is not why I'm here," Barry assured him. "I'm delivering a message from future you to… current you. Like a particularly bizarre messenger pigeon."

"Right." Cisco sighed and headed for the bathroom. "I need aspirin," he muttered. Everything else could wait.

Mercifully, Barry just sat there, munching on the last of his fries, while Cisco found the Tylenol (sitting on the counter, where he'd forgotten to put it away and apparently been ignoring it for at least two weeks) and took two because, obviously, his day was not yet over after all. Then he walked back out and deliberately ignored Barry in favor of the take out menu because, unlike certain speedsters, Cisco hadn't had dinner yet.

Once Cisco's order was placed and the Chinese place down the street promised him delivery in half an hour, he settled down on the couch by Barry. "Okay. So, squawk pigeon. What's the message?"

"Right. So, first, Hartley has information on Ronnie."

Cisco barely refrained from grimacing because of course it came back to Hartley, again.

"He doesn't think his info is useful, though, which is why he hasn't said anything. He's gonna try to trade for something once he does know its useful and you should let him have it."

"Can't you just tell me what he knows?" Cisco complained.

Barry shook his head. "I don't want to screw up the timeline. I'm already pissing off the Time Wraiths who really don't like there being two of one person at any given point in time; I don't want to know what they do to people who don't just cause self-resolving paradoxes but create entirely new timelines instead."

Which, okay, was fair enough.

"Okay, fine. So whatever Hartley wants in trade for what he knows about Ronnie is safe enough. What else?"

Barry glanced mournfully at his now empty fry container and then speedily dumped the remains of his dinner into the trash. Cisco only noticed from the way Barry seemed to 'blink' and the rush of air around him. "Second… Hartley knows something about the Reverse Flash, but he doesn't know he knows it."

Cisco's eyes nearly bug out. "What?!"

"It's… Hartley's never seen the Reverse Flash. At least, not as the Reverse Flash. But he's seen the guy's alter ego doing something that, even out of context, is really weird. Only… Hartley doesn't trust us enough to think we'd believe him even if he told us and even if you were to tell him about the Reverse Flash, he probably wouldn't make the connection himself. Or he would figure it out, conclude that just knowing puts him in danger, and keep his mouth shut. So you're going to have to just wait until he trusts you enough to offer up the information on his own."

There was a moment there when Cisco worried that his internal dialog – which had devolved into some of the foulest cussing he knew in both English and Spanish – might have accidentally been verbalized. But, no, Barry didn't seem to have noticed anything amiss. He'd have probably looked perplexed or a little scandalized if Cisco had actually said any of it out loud.

"And, of course, you can't just out and tell me who the Reverse Flash is either because future me told you not to. Just to torment me with more questions for Hartley – but half of them I can't even ask him yet. What's the point in even telling me all this?"

"So that when Hartley does tell you what he knows, you'll be able to connect the dots yourself," Barry replied evenly.

"Oh." Well, that… made sense. Sort of.

"Okay. Then how do I get Hartley to trust me enough to tell me any of this?" This was gonna suck, whatever it was.

"Don't worry about it too much," Barry told him. "Just… be yourself. I know you probably won't believe me, but the two of you are actually really close when I'm from."

As Barry had guessed, Cisco did not believe him. Cordial he could believe, but close? Not possible.

"Look, you can't… you can't tell anyone about this. My coming to talk to you or anything I just passed on to you from… you. Especially not with Wells. He won't..." Barry cut himself off, jaw tightening and… did something happen with Wells? Because Barry looked almost angry for a few seconds before his expression evened out. "Let's just say you need to ask Hartley about the day he was fired and you'll understand why sharing this information with Wells wouldn't be the greatest idea. He's not always… rational when he thinks he's right about something, even when the facts are stacked against him."

Which didn't sound like Wells at all… did it? Even if it did, what did it have to do with… wait… "Fired? But Wells told us Hartley quit."

"He lied." Barry let that sink in and the stood. "I really do need to get back now. So..." he smiled crookedly and pulled his cowl up over his face. "With any luck, if I get another Time Wraith tail, the Patro-no you guys have been developing will actually work."

"Patro-no? Oh, that is a great name." Cisco paused and then asked, "wait, does this mean that we only named the Patro-no 'Patro-no' because you just told me the name?"

"… Maybe? Look, I'm already just delivering a message to you that you told me to deliver because you remembered me delivering it." Barry let that sink in for a second. "Time travel is confusing."

Cisco nodded in agreement and then sighed. "I guess I'll be seeing you in the future then."

"Yup." Barry hugged Cisco goodbye and then, in a flash of lightning, the future speedster was gone.

Pulling out his wallet, Cisco dug around for a tip for the delivery guy and brought up Netflix. Seemed like a good night for a Doctor Who binge.

Notes:

This is part one in a series leading up to Hartley having a small army of plushy rats as part of an escalating joke with Cisco. Some of its serious, some of its weird humor... hopefully all of it enjoyable.