Author's Note: I'm trying to shake off writer's block, which in this case means pawing through some old writing exercises and seeing where they end up. As you may know, I can't get enough of Amelia's backstory, particularly as it involves Mark, Addison, Derek and the entire Shepherd family. I'm also slightly obsessed with Five Things memes. This was an acing-her-exams present for Summer, so if you're sick of Mark and Amelia, tell her to stop being so smart.

Four Things Mark Taught Amy (And One Amelia Taught Him)

1. A promise can be a betrayal too.

"It's in the treehouse and it's girls only. But I can show you. But If I show you, you can't ask me anything." She looks Mark right in the eye, little heart-shaped face set stubbornly.

"Okay."

"Spit-shake." She props one hand on her hip. "So I know you mean it."

"I mean it."

"Spit-shake anyway."

So he spits into his palm, watches as she does the same, and then her wet little paw slips into his. She pumps his fingers up and down solemnly.

The treasure is a slender silver pendant. He swallows hard on its familiarity. Amy coils the chain like a snake in the small basket of her palm.

"Took it from Kath's room."

Mark looks at her eyes, a pure, clear blue. She's bigger now, half a head taller than the scrunched little thing they peeled off Derek on the night no one likes to remember.

"A boy gave it to her," she whispers.

Mark's promised not to ask questions so he doesn't, but he sees the gleam of metals in the empty cornflakes box and realizes Amy's been hiding little treasures up here like a magpie.

"You going to tell?"

She fixes her eyes on him, challenging.

"A promise is a promise." He shoves his hand, still slightly sticky, into the pocket of his jeans.

Kathleen doesn't notice for weeks and when she does, everyone's there. Everyone's always there, the exact opposite of Mark's own house, siblings all tumbled in the same room like puppies in a bin. The flickering television screen illuminates their face at once, making them look more similar than ordinary light.

Derek's hunched on the battered loveseat fussing over a model plane. Nancy and Kathleen are head to foot on the couch. Jeannie's in the rocking chair, a little distant, maybe preparing herself for when she'll leave for school in the fall. Amy's curled on the rug with her elbow propped on a book and her thumb in her mouth. They're supposed to remind her not to do it when they see it - Carolyn's orders - but Mark accidentally-on-purpose forgets and he's not convinced the others notice.

"Nance, have you seen my silver moon pendant?" Kathleen's voice is airy, like things like this go missing all the time. Maybe they do.

"Nope." Nancy shifts on the couch, summer malaise all over her narrow face.

Kathleen stretches, the bare column of her neck arching like an accusation. "Mark, you remember the one..."

The den feels uncomfortably warm for a moment. He shakes his head slowly, his gaze flickering to Amy.

Her mouth is half open around the wet wrinkled thumb. She bends one bare, scabby knee. Amy's all spaces and angles now. At the pediatrician's office, she told Mark proudly, they measured the spaces between her bones and told her she'd be taller than Nancy. Her front tooth fell out a few days ago and he focuses on the gap where something else will grow.

"Never mind," Kathleen trills and Amy jams her thumb the rest of the way into her mouth.

2. Everything hidden is eventually found.

She's screaming to stop and no one's listening.

They're supposed to be a team, approaching her together, but they're spread out across the room like a battle plan gone awry. Derek's scowling in the corner by an upended trunk; Nancy's dry-eyed and angry with an armload of still-tagged clothing. Kathleen's hovering over Carolyn, who's crying, bent over with her hands on her knees. The rocking chair is moving but no one's in it. Mark stands in the middle of the room, watching Addison try to approach Amy and Amy bat her off.

The evidence is everywhere, amber bottles with someone else's name on them, an old lacrosse sock jammed to the top with condoms, loose plastic baggies of something he doesn't recognize.

Amy slams out of the house and no one follows her. They stand around the detritus of her downfall and look at each other like they have answers. It's Mark who finally lets the porch door swing shut behind him. He's halfway into the jeep when he sees her. She's hasn't run or driven anywhere; she's shimmied up the trunk of the old maple at the edge of the property. The treehouse is rickety now and he's not sure it can hold his weight but he's not sure he cannot do it either. He hauls himself up, the little steps a fraction of what he needs to support him. He heaves himself onto the platform next to her. She's backed against the edge.

He expects her to yell but she's eerily calm. "My father built this," she says.

He moves carefully so he's cross-legged. Something creaks and he feels it within him as he replies: "I know."

The cornflake box is gone. There's metal instead. A strongbox. She used to climb up here in pink fairy wings and they'd chase her while she swung from the rubber tire on its strongest branch. Her hair is a tangled cloud in the faint light, her eyes liquid and huge. The calm scares him more than anything.

He lets his fingers brush the metal and she doesn't stop him. There's paper. He recognizes the state seal and NYU's address before he sees Derek Shepherd, M.D. The pad is half full. He closes his hand around it and she wraps smaller fingers around his wrist.

"No."

"Amy..."

"I need that," she says quietly.

"I know you think you do, but-"

"You have no idea how much I need it."

"Amy, you need help."

She blinks at him.

"Let me help you. I can-"

But she slides to the edge of the paneled floor and jumps.

His heart jumps with her, his fingers just brushing the edge of her jean jacket. Missing her. He pushes himself off and falls heavily beside her, terror in the hands that turn her over. There's a bloodied scratch on her cheek and the wrist he manipulates feels tender but she's in one piece. She's no less okay than she was before.

"Mark! Amy!"

Now everyone is outside. Their timing is terrible.

He searches her pale sweating face for something he recognizes. Strings of damp hair cling to her cheeks. She roars like a lion when they approach her. It's not an expression; it's an actual roar. Her eyes are wild; the calm is gone.

"She's hurt," he says, reaching for her.

"This ends now." Carolyn's voice breaks. "I can't do this anymore."

Nancy puts her arm around her mother. Derek's on her other side, looking at Mark like he can't understand him. Addison is crying - of course she is - but no one moves to comfort her. They're all here for the same reason, aren't they? How can something that's not a face-off feel so much like one?

"Take her to the hospital."

"To set her wrist?"

Carolyn's eyes are almost as dark as Amy's. "Don't bring her back here, Mark."

3. Family is just another word.

He's the only one who shows up. He shoves his hands deep in his pockets and reads her name like a prayer at the wide front desk. Security paces the doors; boxes of tissues are everywhere. Pink, blue, like they're waiting for a baby to be born. Like they're waiting for anything except the moment they can get out of there. Visitor, his badge says. He's one of the lucky ones: he gets to leave.

"You're the brother." The shrink, lanky with bad skin, extends a hand to him. It's slightly sweaty. Mark takes it, shakes hesitantly.

He tries to explain his place, settles on "family friend."

The doctor reads his name off a pad, furrowing his brow. "Mark, right? She told us about you. The older brother."

"No, I-"

But then Amy's walking in, head down, part of a larger group. They're wearing scrubs, not like the doctor she once thought she could be but like patients. Like inmates, really. They're greyish in color and so is she. There's no roaring now; she's pale and dispirited and there's no fight in her he can see.

The group all sits together. He looks from one hunched depressive to the next: this one bloated with recovery, that one sweating out detox. The room smells of too many people all together. The shrink has a smile pasted on his face, a small red stain on his tie. Amelia is looking down at her feet, in cheap tennis shoes.

He thinks about her lie. About all her lies, strung out like beads. At some time he became part of this family, knit up into its texture and there's no way out. Strangers' faces look at him and he no longer cares what they think. What they can figure out. They don't know that Addison cried when he asked her to come with him. Derek says we need distance, she hiccuped into the phone. Fuck that, he snarled, and she cried harder and he was glad. Meanly glad. And he slammed the receiver down and when he saw her at the hospital the next day he cut his eyes at her even though he could tell by the swelling around her nose that she'd probably been awake the whole night in hysterics. A penny for her thoughts. A thousand dollars if Derek was any comfort.

No one wanted to come with him. He gave up on Derek months ago. Nancy was his last resort, and the smirk on her face when she refused-

"Today is Amelia's day," the shrink says brightly. "We're going to talk about her progress and we're going to get to hear from someone in her family who's driven a long way to take part in today's session."

Amelia. The word tastes strange. Amy doesn't look up. There's no sign she hears him. If the others care there's no indication. They're picking at their itching flesh, ripping at cuticles and, in one case, rooting in a nostril. He feels faintly ill. They can't see him.

They don't know what it felt like to drive here alone, that when he stopped at Nancy's twenty miles into Connecticut, and she refused him too, that he snapped. Grabbed her shoulders, asked her why she couldn't care. She raised a hand and he thought she would slap him but she cupped the back of his head instead and yanked his lips to hers. Angry was an understatement for what that was, pushing each other through the house - it was over in minutes and he was breathing hard, sick and sorry. She was cool as a cucumber, only the red pinpricks at her chin any indication he'd been there. Beard burn. She was married and he was the worst one. But then he got back into the car, drove to Amy - the only one, so maybe not the worst.

The old-fashioned wall clock heaves and, with effort, another minute passes.

"Shall we get started, then?" The shrink clears his throat, nods at Mark. "Why don't you introduce yourself."

"I'm Mark," he says. He stares at Amy until her head moves, slightly. She doesn't look at him, not exactly, but he can tell she heard him. "I'm Amelia's family."

4. Sometimes you have to ask for what you need.

He's convinced the light is different here, bluer and cooler. Shades of grey. Light infuses his memory: he sees himself in warm New England autumn. Different. He doesn't belong here, and neither does she. They don't discuss it; he just looks at the way the cold pale light reflects in her pupils and drains another shot. For courage, he tells himself. For the ones who aren't here. The ones we left behind.

"Take me home," she says. His life is complicated but Amelia is straightforward. Direct, insistent, already in his arms before the elevator opens. His key hits the lock and her back hits the wall.

He runs his hands down her sides. She's small but solid, light bones and soft curves. The doctor who predicted her height was wrong. He didn't take into account the cigarettes, a full blown addiction by the age of twelve. Or the stronger stuff. The year in that ward with no sunlight, no way to grow. She's stunted, a hothouse flower. Her skin is warm to the touch and as she wraps her legs around his waist he thinks they are exactly the right length. Amy is gone and she is Amelia, head to toe, no room for anything else.

He touches his mouth to the curve of her thigh and gooseflesh rises in his wake. There's sparse dark hair on her calves, fuzz spreading toward her belly; he's bedded enough women to know what this means: that she wasn't expecting this. That she's been alone and she's been untouched and he sees her as she was, curled like a shrimp on the floor of the den with no one close enough to see her thumb in her mouth.

It should disgust him, maybe. It should put him off - their history and its ugliness and the way her eyes are black with need in the low light. But it doesn't. He slips two fingers inside of her, as warm and wet as that long-ago handshake, and pins her belly to the mattress with his lips. She tastes like airplane, that faint polyester-and-jet-fuel scent, and something else he can't identify, and when she screams he's the one who feels like he's flying. Then she's above him, sinking down until he's surrounded by her, and he lies back and lets it happen because that's what he does.

When she collapses by his side he closes eyes before he can see whether he regrets this. He wipes moisture and hesitation from his face with the back of his arm.

"You have no idea how much I needed that." Her breath tickles his neck. She's face down in the curve of his shoulder, his hand trailing a path from the base of her neck to the dip of her back. His fingers follow the knobs of her spine; he thinks about the flesh underneath. There's a rosy flush to her skin. She's warm and damp: she feels reborn.

I did that, he thinks. He drifts off with his arms around her and wakes up alone.

5. And acceptance can hurt most of all.

He's never seen this bed, this room. The ocean moves gently outside her window and a jar of beach glass rests on the sill. She doesn't want to go outside, Addison said, her shrug at the front door laced with exhaustion. He put his arms around her then, more out of habit than anything else, only a little dismayed to realize she smelled unfamiliar. She dropped her head to his shoulder and he ran a hand down hair shorter than he remembered. He didn't ask her anything about her life, just climbed the stairs with slow purpose. It is as it always has been: Amelia's pain is big enough to eclipse everything else. There will be time, he thinks, to catch up with Addison.

Amelia is lying on her side on lilac sheets. The color is one he'd expect her to hate; with a flash he thinks Addison must have chosen the bedding to look as little as possible like the hospital where they collected her. There are photographs on the rough-hewn dresser and he picks up a small beveled frame. Amelia as a junior bridesmaid, her hand in Addison's. Pictures are lies like everything else; Amelia's sweet and small in the photo, no evidence of what he remembers: her pupils like dinner plates. The tantrum when she refused to leave the hotel.

Her voice, when she speaks, sounds far away. "Derek didn't send you this time."

"No." He approaches cautiously, sits down in the soft chair next to the bed. "I came for you."

"You came because Addison called you."

He thinks for a minute - he's not sure he can comprehend the importance of that distinction. And maybe that's always been his problem. He couldn't see why he had to choose between Derek and Addison and he lost them both. In a choice between Amelia and the truth he already knows how it will come out.

"I'm not going this time," she says. She doesn't have to elaborate. He knows she means rehab and he knows this time means that she's finished. He's not surprised and he doesn't argue. It's gone too far anyway. No one's going to begrudge her pills now.

Then she stands, and that does surprise him. She's frail, the posture of an old woman, but she can move, and she shuffles quietly to his side.

"Amelia-"

He spreads his hands, helpless, and she settles in the open space on his lap. She's light, little bird bones against his legs.

"I'm going to die," she says quietly.

He concentrates on the network of veins at the eggshell surface of her inner arm. "We're all going to die."

"Me sooner than most."

"You don't know that."

"I know a lot of things." She leans back against his chest like she belongs there and he molds his hands carefully, gently around the frame of her ribcage. She feels as hollow and delicate as the vase on the nightstand, but what's inside is darker than flowers, more forbidding.

He doesn't respond to her prompt. She'll continue if she wants to, he thinks, and she does: "I know about Nancy." Her voice is soft. "And Kathleen. I knew about Addie too."

He must have drawn breath at that because she explains: "Before Derek caught you. I saw you, and I knew, and I never said anything."

She's quiet now. All the words seem to have drained her energy.

"I wanted you," she says softly. "I wanted you anyway. I wanted you all along."

She's tired, her breath light and warm on his neck, and he closes his eyes.

This is wrong, it's all upside down. He's supposed to be the one who wanted her anyway, who still loved her in spite of everything. He's the one who kept her secrets and cleaned up her vomit and drove her to rehab and sat in that horrible room with his hands in his lap and watched her come apart. He's the one who gave her something in Seattle, who felt her open under him like a rose, who put her back together. Isn't that what happened?

Tears dampen his collar. One of them is crying.