Mac feels the world tilt briefly sideways while he's waiting to cross Broadway one evening in mid-August. He's on the traffic island by the TKTS booth, being buffeted on all sides by tourists, and as he waits for the light to change in his favor, he happens to glance across the street: not in front of him, to the west side of Broadway, but to his right, to the north, where, on the opposite side of a narrow strip of street, there's another jostling crowd. In the middle of that crowd, standing taller than most of them, is someone Mac thinks he knows. As recognition kicks in, he starts, at least inwardly.

And stares, and the light is still not changing. The moment spins out, and Mac thinks of the desert, thinks of the way a helicopter's rotors sound when it's circling directly overhead. He hears shouts in his memory, not the constant rise and fall of sound here in midtown, but barked orders, just a little too distant for Mac to be able to distinguish any individual words. The muggy heat of summer in New York City is subsumed by a dryer, more intense heat, and the horizon line shimmers in front of his eyes.

The man across the street from him is standing straight, not slouched, hands thrust deep into his pockets. The sun is falling into Mac's eyes and so the man's face is in shadow, a blurred dark center surrounded by a nimbus of early-evening sunlight. It's the posture that Mac recognizes most of all, the tense alertness in the way the man stands, and he thinks there's something familiar about the profile, too. He wants to look away and can't, for fear that he'll find sand drifting over his shoes and into the cuffs of his trousers.

The man may be wearing khaki, or desert camouflage. Mac can't see if he's holding a rifle. But he knows him. And the man he's looking at has been dead for fifteen years.

All of this happens in seconds, and then the sun shifts or Mac blinks, and the figure across the street resolves into someone else. Still someone Mac knows, but not from the desert. It's Flack, just Flack after all, and this is still midtown Manhattan.

The light changes at last and Mac crosses the street, not looking back. Flack catches up with him in the elevator a minute later. "Hey, Mac."

"Flack." This is the end of Flack's first full week back at work - or as close to full as he'll get for awhile: he's on half-shifts right now, but he's showed up early every day and put his hours in, and Mac suspects that he's going to push the limits of how much he's permitted to work. "How's it going?" he asks.

"Fine." Flack reaches out and pushes the button for the 35th floor. "Just getting ready to sign out. You?"

"Coffee run." Mac holds up the iced coffee in his hand, which he'd almost forgotten about. The elevator begins its slow climb up to 35.

Flack takes a closer look at him, frowning a little. "You're sweating."

Mac touches two fingers to his forehead, and they come away damp. "Hot out," he says.

"Yeah." Flack nods, and then they don't say anything else for the rest of the ride. When the door opens, they both look at each other for a moment, then head in opposite directions.

"Good night," Mac calls, when he figures they're a safe distance apart.

Flack turns around but keeps walking, and raises one hand in a wave. "'Night, Mac."

Mac goes into his office and closes the door. This is the way it's been between them all week, and the way it was every time he went to see Flack in the hospital before he was discharged. It's not that they're angry at each other. At least, he feels no anger toward Flack, and is pretty sure there's no animosity on Flack's part, either. Why should there be?

No, Mac thinks as he hangs up his jacket, it's more like they have too much to say to each other, and no words to say it, no way to talk about what happened that morning in May. He doesn't even know how much Flack remembers.

And now there's this, this business of looking at Flack and mistaking him for someone else, of thinking of some other where and when in the midst of that second or two of mistaken identity. Mac shivers a little, remembering those first confused moments of inaccurate recognition. He knows all the scientific and psychological explanations for it, of course: he saw someone familiar, but due to the sun and the positions they were standing in, he hadn't been able to see that person clearly.

The mind struggles, then, to fill in the blank spots and find a context, so it grabs at what it thinks it recognizes and works from there. It happens a hundred times a day. Only, in this case, his mind had leapt to a false conclusion: this, too, happens all the time. It's even logical, after the bombing, that he would in some fashion associate Flack with Beirut, or at least with the Marines. That's all fine.

It's the association of Flack with a dead ex-lover that really troubles him.

He shivers again, then sits up straight and tries to shake off the thought. After awhile, he manages to get back to work. Still, Flack haunts his thoughts the entire the time.

Another week goes by, and Friday evening Mac sits alone in Sullivan's with a beer. Over the past few days, he and Flack have continued to not say very much to each other, except when they're discussing a case. Meanwhile, he's watched Flack joke with and tease Stella and Lindsay, and take their jokes in kind, and he's watched him flirt with fellow officers and go so far as to slap one of the lab techs on the ass. Flack has talked hockey and sushi with Hawkes, and has argued baseball with Danny, and once or twice Mac even saw him talking to Danny in what seemed to be lower, more serious tones.

Flack had been the life of the party all week, the prodigal son, but now it's Friday night and he's here in Sullivan's, and he's as alone as Mac is. He'd exchanged greetings with various people when he first came in, including a brisk nod in Mac's direction, but then he'd retreated to a corner table, and for the last hour he's been sitting back there in silence, nursing a beer and occasionally spitting a peanut shell at the wall, and staring into space.

Mac has no wish to intrude on Flack's private time, but he thinks this might be as good an opportunity as any to talk to him and see how he's really doing. Mac hasn't experienced any more of those moments of time out of joint, of mistaking Flack for someone else, but he's woken up thinking of Beirut more mornings than not, gunfire and mortar shells ripping a desert landscape into rubble.

He stands with his beer and threads his way through the tables. Flack glances up at his approach, and waves to him as he gets closer. Mac stops by the side of the table. "Waiting for anyone?" he asks. He'd thought that everyone had other plans tonight, but he could be wrong.

"Nah," Flack says, "just me. Want to pull up a chair?"

"Sure." Grateful for the invitation, Mac sits down across from him.

"How's the Dradin case going?" Flack asks.

"All right," Mac says. "We're still trying to catch a break, but I think Stella made some progress this afternoon."

"Good. That's good." Flack doesn't really sound like he's thinking about the Dradin case at all, but Mac lets it go.

"How about your cases?" he asks.

"Oh, you know." Flack looks down into his beer. He's too pale; Mac can see that even now, in the uncertain bar light. It doesn't look like he's managed to shave in a day or two, either, which isn't usual for Flack.

"No, I don't know," Mac says. He means it to be gentle, and maybe he succeeds, because Flack shrugs, but doesn't turn away or lose his temper.

"It's impossible to get anything done being on half-shifts, that's all," he says after a pause. "Seems like I just start to make headway on something and then I gotta go clock out. Or go see the damn shrink."

"That won't last forever," Mac says. "You'll be back to full shifts before you know it."

"Easy for you to say," Flack says, looking up at him. "Real fucking easy when you didn't spend two months in the hospital, when the brass figures you're perfectly fit for duty."

"Flack - "

"Sorry." Flack picks a pretzel out of the little bowl on the table. "Sorry, Mac. Just...don't make speeches at me, all right? I get enough of that shit from the shrink."

"Okay," Mac says.

"Okay." Flack presses the palms of his hands flat to the table. "I just want to do my job, is all."

"I know."

"Don't get me wrong. Most of you have been really good about it. You and Danny and Stella, you say, 'Hey, Flack, how you doing?', and then you just let it go. You let me do my work. But some people..." He shakes his head. "That goddamn psych doctor keeps talking about PTSD, like that's supposed to mean something to me. I mean, I know what it is. But I don't see why it has to be relevant to my life."

"It's real," Mac says. "I've seen it happen to people." Shellshock, they used to call it, but he doesn't say that to Flack.

"I know. But why I gotta...you don't have to keep seeing the psych, do you?" Flack asks.

"Only once," Mac says. "Right after the bombing. But I wasn't in the hospital for two months."

"Yeah, but - "

"You don't have to let what happened take over your life," Mac says. "We put things behind us all the time. We let things go. Otherwise, we wouldn't be able to do our jobs. But it's still real. It still happened to you."

"Yeah," Flack says. "And look, I've never been afraid of facing up to anything anyone wants to throw at me. I just don't see the value of picking at the scab, you know? That's why I don't like these appointments."

"Just get through them," Mac says. "The sooner they sign off on you, the sooner you can get back to handling this your own way."

"Good advice." Flack hesitates. "Can we talk about something else now?"

"Sure."

Flack's gaze is focused somewhere across the bar. "Don't mind hanging out for awhile?"

Mac finishes the last of his beer. "What are you drinking?" he asks.

They manage to forget about the bombing for the next hour or so, or at least manage to not talk about it. Mac doesn't know about Flack, but it's in the back of his mind almost all of the time, just the way it has been every day since that Sunday morning. Parts of it have mercifully blurred in his memory - thank God for situational amnesia - but other parts stand out, as cutting and visceral as when they first happened. His hands gone slick with Flack's blood, and the way the building constantly shifted and creaked around them, the steady of rain of dust onto his head and in his eyes. The uncertain twitch of Flack's fingers against his that night in the hospital, and all the hours he'd sat by his bedside.

He and Flack sit and talk about their cases and department gossip, and the chances of having another subway Series this year, and Mac tries very hard the whole time not to think of what Flack looked like that day, helpless and unconscious with half his torso laid open. Just the way he tries not to think of Stella submitting to a rape kit with cuts and bruises on her face whenever he looks at her, and tries not to think of Danny with tears in his eyes and heaving shoulders every time the two of them talk. Like he tries not to think of a ravaged skeleton whenever he comes across that photo of him and Aiden in his desk drawer.

The hits had just kept on coming this spring, and Mac marvels that any of them are still functioning at all.

After he and Flack leave Sullivan's, they go for a walk. They don't discuss this; they just start walking. It's quiet between them for a time, and then, on North Moore Street, Flack comes to an abrupt halt in the middle of the sidewalk. "Mac, listen..." He shoves his hands into his pockets and looks away. The last time Mac saw him standing like this, Flack had just been a man waiting to cross a street. His posture now is more purposeful than it was that evening, though it still has the same watchfulness. Mac thinks for a moment of people who will always, now, be absent, then focuses his attention on Flack. Whatever he's about to say is important, Mac realizes.

"I didn't..." Flack sighs. "I never said thank you."

"For what?" Mac asks.

"I know how it was that day," Flack says. "Danny told me all about it."

Mac has a sudden sense of moving too close to deep water, of the moments right before the bottom drops out from under everything. Talking about Flack's psych appointments and frustration was all right, but this is something else yet again. He also feels ashamed, without knowing why. "I don't - " he starts to say.

"Don't, Mac." Flack begins to pace in front of him, turning in a tight circle on the dark sidewalk, and once again Mac feels time trying to double back on itself. This is Flack, but Mac has been here before. "Don't bullshit me," Flack says. "Not about this. I - I know what you did for me. That day. If you hadn't, I wouldn't be standing here right now."

"I only did what I had to do."

"But you did it. And I'm saying thank you." Flack stops in front of him and looks into his eyes. "Thank you." This close up, Mac can see strands of gray in the hair at Flack's temples. Flack never used to have gray in his hair. But then, Mac never used to have a scar on his chest, and as he thinks that, the old wound begins to throb. Phantom pain.

"You're welcome," he says. "But I just - I had no choice. When I was in Beirut with the Marines - " He stops himself for a moment, then goes on. He told Stella the truth about that day, and Flack deserves no less. "The barracks bombing. Another Marine was wounded the same way you were, and I didn't know how to save him. After that day, I made sure I found out."

Concern flickers across Flack's face. "I'm sorry."

"It was a bad day," Mac says, aware of the understatement.

"Was he a friend of yours?"

"No. I'd never noticed him before. Didn't even know his name until after." After he'd washed the blood off his hands, after they'd counted their dead.

"But you did lose people that day."

"Of course," Mac says. "Other days, too." Some years after he'd known them, years after he'd last spoken to them. News of deaths filtering down to him over comm channels and through the grapevine, the voice in his mind whispering Your ex-lover is dead, and no one but him would ever think to phrase it like that, because no one knew but him - no one still living, anyway.

"I'm sorry," Flack says again, and Mac has the idea that he's watching him closely.

"It's one of the hazards of the job," he says, and meets Flack's gaze. "Not that it gets any easier because of that. I'm glad you're still with us."

Flack ducks his head. "Me too," he says. "But I just - how do you do it, Mac?"

"Do what?" Mac asks.

"I survived," Flack says. "That's great, don't get me wrong. But how - how do you keep on surviving, knowing it coulda all been over? I don't know how - it's my life, Mac. The rest of my life. What do you do once you're a survivor?" His eyes are wide now, the expression in them plaintive and lost.

Various speeches occur to Mac; he rejects them all in favor of the truth once more. "I don't know," he says. "I still don't. Just - live through one day at a time, that's all." It was how he'd managed to go on after Claire had died, too, just living through an hour and then another. Continuing to breathe as the hours turned into days and then years.

And he's still here.

"Just do it," Flack says, and laughs a little.

"I'm sorry. There's not some magic formula."

"No, it's okay." Flack laughs again and shakes his head. "I sorta figured it was something like that."

Mac takes a step closer and puts a hand on Flack's shoulder. "It can help to have someone around who understands," he says.

Flack looks at him. "Yeah," he says. "I guess it can." Mac smiles, and Flack claps a hand on his shoulder. It turns into a semi-embrace, and Flack pounds him on the back. "Thanks, Mac," he says in a low voice.

"Any time," Mac says. Flack's arms are warm, and Mac can, faintly, feel the beat of his heart in his chest. It's a soothing rhythm, and it takes Mac a little too long to realize that propriety dictates that they really should have let go of each other by now. By the time it does occur to him, he finds himself disinclined to let go of Flack. Flack, who could have died too, but didn't. Flack, who finally squeezed his hand.

Flack's lips brush his cheek, and he doesn't pull away. He turns his head, instead, and presses his mouth to Flack's cheek, mirroring the kiss. Rough skin, the scratch of stubble; he hears Flack draw in a shaky breath, and then he pulls back a little and looks into Mac's eyes. Mac takes a quick and instinctive glance up and down the street to make sure it's still empty, then leans in and kisses Flack for real.

It's all sharp angles even as the kiss deepens and as Flack wraps his arms around Mac's back and pulls him in close, Flack's mouth hot against his. Hot hard mouth, cop mouth, and Mac kisses him and thinks of how quickly a man's fortunes can change, how fast it can all fall apart. A sandstorm rages behind his closed eyelids, and the kiss is good; he can feel the life pulsing in his veins, the same life that beats in Flack's strong heart, their shared breath as they keep on kissing each other. Flack's tongue slides across his and he bites at Mac's lower lip, gasping a little as they press into each other.

Flack is the first one to break the kiss, but even then he doesn't pull away; he rests his forehead against Mac's, breathing in shallow gasps, and presses one more kiss to Mac's cheek.

"Come home with me," Flack whispers against his mouth. "Just for tonight. I don't wanna be alone."

"All right," Mac says, and strokes a hand down Flack's face. He doesn't want to be alone, either.

"I'll get through this," Flack says.

"Of course you will." People like them always do find a way to keep going - but he doesn't tell Flack this, not right then, anyway, because he doesn't think it would be a comfort. Mac promises himself that if he ever masters the trick of not looking back, of letting go of the past once and for all, he'll share the secret with Flack.

"Okay," Flack says, and his hands tighten on Mac's waist as he starts to kiss him again.

They clutch at each other, two survivors on North Moore Street in New York City, and the night deepens around them.