Quick head's up: This follows my one-shot 'Performance Review,' but it can be read as a stand-alone.

Longer head's up: This series of one-shots begins with 'The Memo' in my other one-shot collection, Inertia. However, these Singh stories stopped being stand-alone one-shots and instead became their own continuity, so I've decided that any new Singh stories will be posted here under the Internal Affairs banner instead. To avoid treading on the toes of ffnet's policy regarding duplicate posts, I have not copied the first three installments over. They are, in order: 'The Memo,' 'The Follow-Up,' and 'Performance Review.'

Title: Rules and Regulations
Summary: Tag to 3x05, with an Internal Affairs spin! Singh POV

"Sir, Captain, that's it? I document eight different - "

"Nine," David corrected, glancing at the report on his desk.

"Nine different violations of regulations and he gets a fifteen-second talking-to? Must be nice," Albert muttered.

"Oh, I'm not done with him yet. You can go, though, Mr. Albert."

Albert scowled, no doubt disappointed he wouldn't get to witness Allen getting rebuked, but he nodded formally - "Captain." - and walked briskly out the door, with a bit of a spring in his step (probably feeling smugly vindicated, to have been right about Allen. Or maybe it was simply schadenfreude).

David waited until the door was fully closed and Albert was on the far side of the bullpen before he turned back to Barry, who had tentatively sat down and was jittering one foot nervously.

"Allen. You've got to be more discrete."

"…Captain?"

"I cut you as much slack as I can, but that only works as long as no one else notices." He glared at his errant CSI, who continued to look inexplicably gobsmacked, as though David were speaking a foreign language. "If you keep this up, people are going to start throwing accusations of favoritism around - you do understand that I'll have to start taking a harder line with you before it gets to that point, don't you?"

"Um, Captain Singh, sir, I don't think I follow."

"Clearly." David suppressed the urge to roll his eyes. "Whatever happened to our arrangement? I thought it was working out well. Did something change?"

"Um, could you maybe… refresh my memory? I'm drawing a bit of a blank, sorry. What arrangement?"

David scrutinized the young man in front of him closely. He certainly looked like Barry Allen, and he sounded exactly like him, but if he'd been replaced with a doppleganger then it was vital that this conversation - about the arrangement David had with the Flash - go no further.

"Before I do, why don't you do something for me first. Could you please verify that you are, in fact, the Barry Allen of this Earth?"

Barry somehow managed to fall out of his chair in shock. (His cup of coffee miraculously managed not to spill, and David had a few ideas about how he manged that. Well, one idea, but it was a solid one). Barry sat on the floor, mouth hanging loosely open as he stared up at David, before he came to his senses and scrambled back into his seat.

"Wh-what do you mean 'this Earth?' There's just the one planet, right? Ha ha."

David tensed. "If you really were Barry Allen," he said, one hand creeping under his desk, "you would know the answer to that."

He pressed the Flash panic button and held his breath, waiting for help to arrive.

And kept waiting.

Across from him, a phone chimed; the imposter glanced at his text message and then turned back to David. "He says it's an emergency - can I please take this call?"

"You can answer so long as you stay right here where I can see you."

Clearly conflicted, the imposter waffled for a moment, eyeing the door as though considering whether it would be worth it to go against orders and leave anyway. Evidently the emergency was urgent enough that rather than press his luck, he decided to return the call in David's office.

"Cisco, what's… What do mean, Singh tripped the alarm? What alarm?" The man jolted to his feet.

David watched as his expression changed, from concern to wide-eyed shock, as he stared open-mouthed at David for the second time that day.

"What do you mean Singh knows?!" he yelped loudly. He continued to gape as he listened to whatever Ramon was saying on the other end of the line.

David raised one eyebrow placidly. He still didn't know what was going on, but he wasn't going to let that be known.

Slowly, Barry – if it was Barry – lowered himself back into his chair. "No, everything's fine here… he's right in front of me, of course I'm sure… yeah, see you later. Bye."

He ran his fingers through his hair, a nervous gesture - he kept glancing at David and then away, flustered, and David was reminded of their first conversation about meta-humans, over a year ago. If this really was his Barry Allen, how had they gone back to square one?

"I guess this means, since you wanted me to prove my identity, I can tell you that I'm the Flash." He paused a moment, in which he gulped visibly. "Ta-daa." Barry's jazz-hands vibrated as before, and David's feelings of déjà vu deepened.

"Why don't you remember any of this? Any of what we've talked about?"

Barry sighed mightily. "It's a long story…"

"Is it amnesia? I thought you had a healing factor… though I suppose that didn't help Wolverine much."

"You like the X-Men?" Barry perked up, seemingly poised to pursue that tangent before he shook his head. "Nevermind. It's not amnesia. Well, maybe it's true that it's got similar symptoms, but there's nothing wrong with my brain. And I didn't forget, the memories just… were never there."

'Were never there' was an odd verb tense to use, but it was one he'd heard before. "Is it time travel again? It is, isn't it."

"How do you know about that?!"

"You told me."

David rubbed his temples as the full extent of the problem became evident: what Barry remembered and what actually happened (in this timeline, which was the only timeline David had ever known or would ever know) did not match up. And Barry obviously wouldn't know where the mismatches were until they presented themselves, in the form of missing knowledge (or, as with Barry's familiarity with Rob, knowledge where there should be ignorance).

But he and Barry had had their first heart-to-heart over a year ago! And Barry still remembered everything as recently as last month!

"How far back did you go? And why did your memories suddenly change now?"

"Far. I went back far, went… too far. And I tried to undo what I did, but… Chaos Theory, maybe, or something. Little, imperceptible differences growing and changing things. As for why now... This time, I ran forward in time, afterward, to return to when I left. I got back a few weeks ago, and that's when, from your perspective, my memories changed." He shuffled his feet, his expression somber and unusually grim.

David remembered everything Barry had ever told him about time travel. He especially remembered when he first learned it was possible, and a distraught Barry speaking in a choked-up voice: "Time… finds ways to compensate. Otherwise… Otherwise what's to stop us from just… g-going back an-and f-fixing things?"

"What exactly was our arrangement?" Barry broke the silence.

"It was very straightforward. You tell me when you need to run off, and I'll send you out on 'assignment' so you aren't taking unauthorized absences from work."

"Oh. Cool. Yeah, can we do that again? That sounds really nice."

David narrowed his eyes at him. "Only so long as you don't abuse the privilege, Allen. As I said, I can only cover for you as long as no one notices."

"I promise." Barry nodded vigorously. "…So, who the heck is Julian?"

David pinched the bridge of his nose, trying to stave off a headache. This conversation was beginning to look like it could go on indefinitely. "He's a meta-human specialist, and the senior tech in your lab. We couldn't just keep relying on Ramon for all our meta-human solutions; his availability was too inconsistent, especially when he went haring back to STAR Labs at the first whiff of trouble. I'm sure you can see how that would send the wrong message to the rest of the force about our preparedness. And hiring another CSI cut your workload in half, gives you more time to do what you need to do."

"But now it takes forever to get anything done in the lab; I have to go slow all the time."

David snorted, unimpressed. "You shouldn't have been using your speed in the precinct in the first place - anyone could have walked in at any time."

"Yeah, but - "

"Allen. Moving at a normal pace isn't going to kill you."

"It could. If a bullet was coming for me or a building was falling, normal speed would definitely kill me."

"You're sharing your lab now. Deal with it."

Barry groaned and rolled his eyes theatrically. David cleared his throat pointedly, and Barry immediately straightened his posture, ducking his head apologetically.

"If that's all, Mr. Allen, I do have other work I need to get to, as do you. I'll… try to pull together some sort of summary of what you might – or might not have? – missed."

Barry thanked him and turned to leave. David tapped his fingers restlessly, feeling conflicted about whether or not to ask his next question, or if he was happier not knowing.

"The other Barry – the Barry from my timeline – what happened to him? When you time-traveled?" he finally blurted.

Barry froze, one hand on the doorknob, and turned his head to look back at him. His stricken expression was all the answer David needed, and he waved Barry out the door before he could open his mouth.

Something in his chest felt tight with an emotion that felt a lot like grief, for what was lost. He doggedly reminded himself that if they could reach that level of trust once before, they could reach it again. Over and over he repeated it, like a mantra.

They could be friends again.