please heed warnings, as this fic does discuss/flash back to a (nonsuccessful) suicide attempt when mark and derek were in college. second fic set in a grey's anatomy zombie apocalypse au. not written with any romantic pairing in mind, but feel free to interpret things how you want.

for my h/c bingo prompt "suicide attempt"

what's gonna be left of the world

if you're not in it?

what's gonna be left of the world, oh

every minute and every hour

i miss you, i miss you, i miss you more

- bastille, "good grief"

The fact that they're on the roof when the conversation occurs has got to be some sort of sick cosmic joke. Of course, there are limited options for privacy these days, and outside of your shift on the roof with your assigned patrol partner guaranteed one-on-one talking opportunities are few and far between. So it's on the roof of the hospital with Meredith that Derek starts talking one night, walking next to her in the light mist-rain and speaking out of nowhere, voice almost echoing in the otherwise empty air.

"I can't stop thinking about Mark," he says, and he doesn't look at her when he says it. He looks out across to Puget Sound, where no ferryboat has graced the waters in a long time, takes in the ghostly skyline.

Seattle wasn't wrecked the way other cities were, cities where the CDC had major offices, cities where black helos rained down fire and destruction, leaving the jagged, ruined corpses of hollowed buildings in their wake. From a distance, Seattle almost looks the same. When you got a closer look, however, peered at the streets more carefully, the awful stillness becomes clear. The windows of the Space Needle are dark and quiet, all the lights that normally decorated the skyline like a proud Christmas tree extinguished.

"Mark," Meredith repeats, and her voice is mostly neutral, with a hint of surprise, confusion. She knows who Mark is, remembers the story from the steps of Derek's trailer, once upon a time just after Addison appeared and everything seemed so complicated but was really so simple. Meredith knows who Mark is. She knows what Mark did.

"Yeah." As he turns at the corner of the roof, shifting the rifle he carries, Derek's voice has gone soft and wilted. Meredith can remember how he'd sounded when he told her the events that led to his flight from East Coast to West. He sounds nothing like that now. His voice has lost the rough edge of anger, and the sadness that tinges it doesn't sound wounded like it did then. It sounds wounded in a different way, a more permanent way that speaks to the kind of regret you know you can never make right.

"I thought you hated him." Most of Meredith isn't sure why she says what she does, why she continues dredging up pieces of The Old Life, pieces he clearly would prefer to leave there, but the curiosity is just a little too strong. Why Mark, and why now.

"I did." Derek makes a face, footsteps faltering for a moment in their steady rhythm on the damp pavement. "No. I didn't. I tried to, but I never could. I was angry at him, but I didn't hate him. I don't think I could ever hate Mark."

Meredith doesn't think he could either, which is a theory she's refrained from voicing. They're not together now, she and Derek, not technically, but she still knows him like a well-worn routine, and Derek has never been good at hating anything. 'McDreamy' was about his eyes and his hair, the way he smiles, but it was about something else too, about the way he looked at brain scans like artwork and always saw the best in people. The way he'd talked about Mark, the scarce times the man had come up, the mythical figure Meredith didn't have a face to put to the name of, she can tell it was someone Derek had loved. Still loves. And Derek, bless his stupid tender heart, can't hate someone he loves. Meredith should know. She'd watched him try and hate Addison for long enough.

'I'm sorry', she would have said, Before. Now though, After, she can't. There have been too many 'I'm sorry's, too many losses, too many platitudes that were never good enough to absorb the expanse of grief hanging in the air as thick as the fog over the Sound.

"I always thought I'd have time," Derek says, still talking in that odd, half-empty voice that sends shivers up Meredith's spine. "Time to fix things, you know? I never thought, when I left, that it would be the last time I ever… If I had gotten a call, while I was here, after I left New York but before Addison showed up, if someone had called and said 'he's dying', I-" His voice breaks a little, and he clears his throat. Still he doesn't look at her, looks out over the roof's edge, sneakers lowly beating out a well worn pattern on the surface. "I'd have gone in a second. I thought…"

"He could still be alive," and normally it's Derek's job to say things like that, Derek's job to look at the clouds and draw a silver lining with a pen tucked into his ferryboat scrub cap, but Meredith hasn't seen him wear one of those in weeks and right now his well of ink doesn't seem silver so much as leaden.

"He's not." There's a finality to how he says it that sends a pulse through her gut, a sharp ache that makes her want to go downstairs, find Cristina, find Alex, find everyone she loves and corral them all into one room, count the colors of their eyes and the rhythm of their breaths until she's sure they're still there.

"He could be. We're still here, aren't we? He could be out there somewhere."

"He's out there somewhere, unless he-" Derek's words cut off and he looks down at his hands, feels the nauseatingly foreign weight of the gun in them, stares at the weapon he hates so much rather than look Meredith in the eyes as he admits what he's so, so deathly afraid has happened to Mark. What he's afraid Mark's done. "Unless he isn't." He swallows, tries to laugh, to coax even a breathless chuckle out of his lungs to break the tension that's fallen over them. What escapes is some kind of choked sound he can't or doesn't want to find the name of. "He never was good at being alone."

"Derek."

"We were in college." His voice is weighed down, wrapped in a fisherman's net and sank to the bottom of the Sound. "I found him on the roof."

Matthews Hall was a hellhole of a dorm building, but it was also the tallest one on campus. The walls reached into the sky above the others, just a few stories, but enough to make it impossible to miss. When they moved in that year, it had quickly become Mark's favorite spot. You could see the whole night sky from there, he claimed, even though Derek waved an astronomy textbook at him and said something or other about light pollution.

Since the beginning of the year, Derek had known something was wrong. Mark had never exactly been the happiest of people, the most stable or secure. He'd had a rocky Sophomore year from the start though, and it was mid-November when it all tumbled into a landslide, when Derek came home after class and found Mark sitting on the kitchen floor with his back to a cabinet, staring at the fridge like he was trying to remember what he was doing there. He'd explained, when Derek pulled him off the floor and led him to the couch, freaked out and doing a semi-passable job of hiding it, that he'd gone to get something out of the fridge and ran out of energy halfway there, sinking onto the tile and staring, just until he felt like he could get up again.

If Derek hadn't gotten home when he did, who knows what time Mark would have gotten up.

Coming home to that, however alarming it was, was nothing compared to coming home to an empty room. Mark wasn't there, not when Derek poked his head into their room, not when he walked around the shared kitchen, the cramped living room, the laundry room on the bottom floor. Mark wasn't anywhere, not that Derek could find, not until he remembered seeing something upstairs, on Derek's desk. He'd figured it was some assignment of his that had ended up on Mark's side of the room, but now he wasn't so sure, and the speed of his steps going up the staircase to the fourteenth floor correlated to the mounting panic in his chest.

Mark still wasn't there, but the note was.

When Derek got to the roof, he almost collapsed onto the snow-dusted ground right then and there. Mark was standing at the edge without his coat on, hands hanging limply at his sides, staring directly down at the walkway below him.

"He didn't jump, and he got into counseling the next day, at the student center, but…" Derek shakes his head, and Meredith can see the ghost of Sophomore year, Matthews Hall in his eyes, haunting him. "I couldn't ever forget it, couldn't ever shake the thought that one day I'd get a call from someone telling me he'd- I never told him I loved him, you know that? Not once. He was my family, and he did something bad, but I- If I'd known I'd never have another chance, I'd have told him. But I didn't, and now I can't."

Meredith doesn't know how to answer that. She bows her head and bites her tongue and looks out off the roof, down at the perimeter barricades. It takes Derek's breathing a long time to calm.

It's Addison that gives them the news, that bursts into the room one day gasping a name that sends Derek running.

When they finally see each other again, Mark doesn't know what to expect. A withering glare, a turned back and swift footsteps away, a fist to his jaw - honestly, he'd deserve any of that and worse. Rather than any of that, though, what Derek does is the last thing Mark is expecting him to do. The hand that extends out towards him is shaking, but Mark doesn't think it's anger causing it to. There's a brief moment of a palm against the side of his face, a thumb against his cheekbone, fingers grazing his hair, before Derek yanks him into a fierce embrace, harder than Mark has been hugged since a cold night in October, standing on the roof of his Sophomore year dorm building.

For the life of him, Mark doesn't understand what's happening. The desperation in the way Derek is clutching him, like Mark is something precious he'd thought was gone for good, it infects Mark as well, until he's holding back nearly as tightly, a lump in his throat and a faint roaring sound in his ears.

Instead of explaining himself, Derek screws his eyes shut and shakes his head. His chin digs into Mark's shoulder and his hand is gripping tight to the back of Mark's neck, stopping just short of painful. Derek doesn't speak, just presses Mark harder to his chest, because there are no words for what he'd been afraid of. Language does not contain the capacity, in this moment in time, to lay out the blueprints of the list he'd drawn up in his mind, factors against Mark's chances of survival. Derek has seen people die before, patients of course, but more than that, he's seen people he loved leave him even as he prayed they would stay, very nearly seen Mark add himself to that list. He was able to imagine with all too sharp a clarity, just how it would have felt to watch Mark die.

It was a short step, then, from imagining to accepting it into reality. Somewhere between that night on the roof with Meredith and the day Mark had stumbled, bleeding but mostly okay, back into his world, Derek's hypothetical that Mark had killed himself before the undead got the chance to had phased from 'possible' to 'probable' to 'no longer able to imagine any other outcome'.

Derek Shepherd, who had always had a way with noble speeches, doesn't have any words to tell Mark Sloan 'I was terrified you'd gone back to the roof and I wasn't there to pull you down this time', doesn't have the strength to confess how he had carried the guilt of Mark's suicide around in his chest for months, cradled between his collarbones like Mark's very soul had caged itself in his ribs. So instead of even trying, he just tightens his fist in the back of Mark's shirt until he can feel his knuckles creak and tries to tamp the uncontrollable sobbing he can feel building in him down, at least until he's alone.

"So, can I assume this means you don't hate me anymore?" It tries to be a joke, but it's too raw, like if you scraped the surface of the question with the edge of a knife the thin layer of humor would flake away and there that terrible hope would be under it, just like it always was.

As it stands, Derek feels as if that very knife has then been jammed into what, in the tiny part of his brain not reeling from what he's heard, he thinks is probably his sixth intercostal space, recoils on instinct. His head snaps back and he looks Mark in the eyes, 'you've got to be fucking kidding me, right' just on the edge of coming out of his mouth when that tiny part of his brain still capable of thought reminds him exactly how that was likely to be taken.

"I-"

I don't hate you-

I couldn't hate you-

I tried believe me I tried to-

I never-

I loved you, even when I tried to hate you-

Whichever of those things he'd been planning to say, all of them surging forward to be what makes it out of his mouth first, the point is rendered moot because all that actually succeeds is that first strangled sob, and then it really is all over. Derek gives up on any semblance of having his shit together and pulls Mark back into his arms. Somewhere amongst heaving shoulders and damp gasping breathing, Derek thinks he says 'I'm sorry', over and over like a record caught on a loop.

"I think you stole my line."

"I love you."

Another weak attempt at a joke clashes with the brutal honesty that Derek blurts out in response, barely a beat between the sentences. It's so incongruous with the last time they spoke before today, takes Mark so completely by surprise that he pulls back to look Derek in the face, a bewildered, "What?" escaping before he has the chance to stop it.

"I said I love you," Derek repeats, quickly and easily, unable to think about anything but how it had stuck in his throat when he was nineteen.

"Mark," Derek called, hoping his voice only sounds that shaky to his own ears. "Mark, please get back."

No answer.

"Mark. Please."

"I tried to jump."

Derek's heart stopped, and before he could think of anything to say, Mark kept talking.

"I couldn't do it." His voice is dull and empty, and his cheeks are red from cold. His eyes are reddened for a different reason, and they're too bright, too wet. "I tried, but I couldn't do it, Derek."

When Mark still didn't get away from the edge, Derek stepped forward instead, reaching out slowly, not wanting to startle him for fear of sending him over the edge and into the swirling snow and wind below. Mark didn't move, letting Derek grab the back of his sweater and pull him away. He stumbled over a patch of ice and Derek caught him, pulling Mark right against him, one arm iron around Mark's back, other hand pressing his shivering best friend's head to his shoulder.

'Please don't ever do this again, Mark, please, call me if you want to, I don't care what time, just never try something like this again', Derek wanted to say. He wanted to say 'you're my best friend, I love you', but it just wouldn't come out.

Nothing came out, so Derek just held on tighter than felt possible and tried to figure out what he was supposed to do now.

He hadn't been able to get it out, on the roof that night, and had never found the opportunity to work it in later, no easy way to grab his imitation-bravado-brave best friend by the arm and say 'by the way, I meant to tell you I loved you but couldn't quite manage it, and I want you to know that I do'. It had been simpler to just adopt the logic that Mark must know , after what happened at the highest point of Matthews Hall and the lowest point of Mark's life.

So, can I assume this means you don't hate me any more?

Clearly, that logic had been faulty.

He never was good at being alone.

Maybe if, before Seattle, before Addison, before Matthews Hall, Derek had said it, they could have avoided this. Maybe if Mark had known, things wouldn't have gone so badly.

(Thinking about why, exactly, Mark needed such things laid out in front of him with the subtlety of a pillowcase full of bricks never did anything but make Derek very, very mad, so he avoids that particular route at the moment, opting instead to focus on things he can undo.)

"I should have said it before- Before what happened." Love aside, forgiveness and loss and apocalypse aside, it still stings him to think about, but not nearly in the acid-cruel way the mental image of Mark swallowing a handful of pills or a bullet had, and if there's one thing to be said for what the end of the world has done for Derek Shepherd, it has laid his priorities out for him exceedingly clearly. "I'm sorry I didn't."

It's about the most genuinely happy Mark has ever looked, like he honestly doesn't know if he believes what he's hearing, and there's that helpless anger again, a coal fire in Derek's gut that ignited when he was a teenager and has never really gone away.

"I love you," Derek says again, one more time for good measure, moving slower and calmer this time when he draws Mark again into his arms, if only because he, by the grace of god, has the option to.

"I love you, too," Mark says in return, in a voice muffled by Derek's coat and the confused wonder that this is even happening at all, and Derek catches a glimpse of Meredith over his shoulder. She's lounging on a bench with Cristina, and Derek lets go of Mark long enough to wave her over.

After all, there's someone he needs to introduce her to.