So I started writing this straight after last Saturday's episode and have only just got it finished in time for today's. This is set following 'Sweet child of mine' after Cal fails to get a reaction from Ethan by pushing him and encouraging him to hit him. Probably some of this will contradict what happens tonight, so please try to ignore the episode if you don't read this until afterwards.

I hope you enjoy (wrong word?) reading this and I would absolutely love it if you can leave your thoughts.

Cal arrives home to discover the television on twice the volume it should be. He shrugs his bag from his shoulder and is about to lower it to its usual home on the floor, when he realises the spot is already occupied. Ethan's briefcase is half open and paperwork is spilling out.

Cal crouches and retrieves the top sheet of paper. He recognises Ethan's undecipherable handwriting as immediately as if it were his own. The page lacks a heading but displays a myriad of scribbled words and phrases, medical terminology and bullet pointed symptoms. He groans. He's done the research himself, of course, both prior to and following Ethan's diagnosis. There's a torture in knowing, in learning every symptoms and memorising exactly how the disease steals a life. He envies those who can lives in ignorance.

"Ethan!" he calls.

There is no response. It's hardly a surprise; the television's deafening.

Cal paces to the centre of the room and snatches the remote from the seat of the sofa. His finger skips over the volume decrease straight to the off button. The room drops into silence and for a moment Cal wonders if he preferred the inane prattle of the TV.

"Ethan?"

He hears a metallic crash as something is slammed onto a work surface and then his little brother emerges from the kitchen. Ethan keeps himself half hidden behind the dividing wall and Cal almost scoffs at the futility of it. He doesn't need to see a physical barrier to understand that Ethan's putting up walls.

Cal realises from the way his brother's eyes flicker to the blank television screen that he objects to it being switched off. He waits for Ethan to make a cutting comment about his lack of consideration but there's nothing further except silence. Evidently, verbalising his complaint would break the self-imposed reticence that Ethan has clung onto for days.

Cal longs for a reaction, an outburst. Insults and punches and tears would all be easier than this black hole that has encased his little brother.

"About earlier," Cal offers. "I'm sorry. That was stupid of me."

Ethan raises his eyebrows but doesn't comment.

Cal sighs. It's not often he offers himself up for criticism from his brother and even rarer for Ethan not to have pointed it out first. He knows he's handling this badly, knows he's letting his brother down. But he's tried everything and Ethan's barely uttered a word.

"I saw your research," Cal says.

He studies his brother's face close enough to gage the flash of anger in Ethan's eyes. Cal holds his breath and hopes this is the moment Ethan snaps. He knows Ethan hates it when he fails to respect their mutual privacy and surely going through his bag crosses any boundaries. But the anger is quickly replaced by another look, one which grabs hold of Cal's heart and squeezes it tightly.

Ethan looks scared.

But by the time Cal steps forwards, his little brother's mask is well and truly back in place. The new normal, this perpetual blankness, reveals nothing and everything and Cal doesn't know what to do. He holds his arms out towards his brother and for a moment Ethan seems to sway towards him. But then he falls into a walk and he hurries from the room.

Cal's lost count of the amount of times he's stared at Ethan's retreating back. Sometimes he lets Ethan go; today he follows. The bedroom door is slammed in his face but he flings it straight back open because any hesitation would mean he'd have to think things through.

"Ethan-"

"Get out."

It's the first thing Ethan's said to him since he got home and it's laced with fury.

"No," Cal says.

He can see the tremble in Ethan's bottom lip as he fights to stay in control. It's so typically Ethan that he nearly smiles. But then Ethan straightens his glasses and looks him square in the eye with a steely resolve.

"Fine. Then I'll go."

Cal suffers two seconds of shock and so Ethan's nearly out of the door by the time he comes to his senses and all he can grab is Ethan's wrist. He yanks his brother back into the room. There's no doubt that it hurts, for Ethan snatches his arm back and rubs at the joint.

All Cal wants is for Ethan to talk to him, for there to be some recognition of the moment they swore they'd move forwards as brothers. But Ethan's already edging back towards the exit and there's no time to compose the right words.

"You can't shut me out forever," he says.

Ethan rubs at his temple as if just being near Cal is enough to give him a headache. "I can get used to being without you."

"What?"

"Well, you're going to leave, aren't you? We both know it." Ethan takes a deep breath. "The only question is when. When I'm forced to leave my job and can no longer contribute so much to the rent? When I'm given a wheelchair and can no longer clean up after you? When I can barely speak or eat or wash myself?" His voice shakes. "I don't intend to spend the rest of my short life wondering when you're going to leave, Caleb. You may as well do it now."

Cal's stunned into silence. Ethan's given him a week's worth of words in one go and he doesn't know how to comprehend a single one. He's winded with the realisation of how much of a lousy brother he's been for Ethan to think of him like that.

"No," he stammers. "Ethan, you've got me all wrong."

Ethan scoffs.

"I'm being serious," Cal says. "Look, I know I've not always been the best brother to you. I know that and I'm sorry. But I promise you, Ethan, I promise you that from now on I'm going to be there for you." He pauses long enough to scrutinise his brother's face but Ethan's forced composure prevails and Cal hasn't a clue what he's thinking. "It doesn't matter what," he continues, "I will help with it. When the time comes, I will carry you out of your wheelchair, I will cook you food, I'll blend it if that's easier, I will-"

"Stop it!" Ethan snaps. "Just shut up!"

Cal's not sure exactly where he went wrong this time but knows he's messed up somehow. He squeezes his eyes shut. He just wants to reassure his brother and he's determined that Ethan will listen. "I will administer your medication," he perseveres. "I'll wash you, I'll take you to the toil-"

The final syllable is lost from Cal's lips as Ethan throws himself at him. Cal's back smacks against the wall and he gasps, although it's more from shock than pain. They're chest to chest now and Cal can hear every trembling breath that his little brother's takes.

He's sure that Ethan's about to hit him and even though he knows first-hand how much Ethan's fists can hurt, he's glad. His brother can unleash as many blows as he likes as long as it shakes him from his emotionless stupor. He reminds himself that he deserves it anyway, his own punishment for getting the all clear.

But the punch never comes. Ethan shoves him one more time and then releases him, stalks to the other side of the bedroom. It feels worse that he didn't get hit. It's testimony to the fact that Ethan is a good person even when the world is crushing him from every angle.

"You don't get it," Ethan says. "I don't want you to be my… my carer." He spits the word out in disgust. "I just want you to be my big brother."

Ethan thinks it's preposterous, really, for Cal to have been following him so persistently over the last few days. Nothing Cal can do or say will change anything. He has Huntington's. He has genetically acquired Huntington's disease and it's going to kill him. It's going to slowly and painfully tear away everything he loves and leave him entirely dependent on someone else.

They're both doctors. They both know the facts.

And yet, Cal seems to think talking is going to help.

Ethan notices his brother shuffle nearer to him and so raises his palm as a stop sign. His hand is steady but he can't help wonder how long it will be before involuntary twitches engulf every movement. He hates himself for thinking like this before he has to, hates that his mind has betrayed him and that his body will one day do the same. He hates how even before the symptoms strike the disease still taints every thought.

Cal, unusually, takes the hint and falters to a standstill in the middle of the room. He looks awkward and concerned and like a small boy who's just been told off for making an inappropriate comment. It doesn't suit him one bit.

There's a moment, when their eyes meet, that Ethan's self-control nearly wilts. He wants to hit Cal; he wants to punch him so hard that he wipes that pitying look off his face. He wants to plough his fists into Cal over and over until every bit of rage has left his body. But he knows his brother wants it too and perhaps that's why he resists. Cal's looking for an excuse to make it all about him and Ethan's had enough of that to last a lifetime.

Besides, even if he beat his brother into a bloody mess, he'd still be left with Huntington's.

"I'll always be your big brother," Cal tells him.

Ethan turns away. It's easier to ignore Cal than to try and explain why the statement did nothing to reassure him, why the only fragments of faith he had left in his brother have vanished so rapidly. Cal lied to him; it was as simple as that. Cal lied to him and now he has Huntington's disease.

Ethan knows it makes no sense to blame Cal. He knows their results would have read the same regardless of his brother's behaviour. But he can't help but imagine the outcome if karma had stopped to consider which of them deserved it more.

He hears a whisper of a name and then feels a hand clamp down on his shoulder. He jumps despite the warning. Cal manoeuvres him so that they're back facing each other but Ethan shudders out of the grip. He doesn't want Cal moving him around while he has the full autonomy to do so himself.

"Ethan," Cal repeats, a little louder this time. "Come on, mate. Talk to me."

It's a struggle to even look at Cal without feeling like someone's poured tar down his windpipe. Cal reminds him of everything he'd rather forget. Cal's the reason he can't forget. His brother is blessed with perfect health and that mutilates everything between them.

Ethan shakes his head. He doesn't know what he's renouncing but it may as well be this new situation, this terrifying life sentence. He can't do this. He objects. He's saying no. It makes no sense that people have tolerated this before him because how can anyone live knowing the tiny details of how they will die? He can't accept this. The test must have been wrong. It just must have.

But he knows denial; he knows it and has treated many severe cases of it. It's a common side effect of bad news and he's not fully understood it until now. But he's a doctor. He'll always be a doctor, even when his job gets stolen from him like everything else. He has to believe the facts. The Huntington's going to destroy him and there's nothing anyone can do.

It's as if he's reading the results all over again.

His knees buckle.

Strong arms catch him and haul him back upwards. He doesn't want to be caught; he wants to feel the pain from his shins smacking the floor. He wants a distraction. But Cal's already taken that choice from him and now he's stuck in an angry embrace.

"Get off me," he hisses into Cal's t-shirt.

His brother squeezes him tighter. Ethan cannot move. He may as well be suffocating.

"I mean it, Caleb. Let go!"

"Not unless you talk to me. Tell me how I can help."

"Help?" Ethan splutters. As even the most accomplished doctors cannot help him, it's ludicrous that his brother wants to try.

He wriggles, directs an elbow into Cal's stomach, stamps on his brother's foot. He hears Cal grunt but the grip is firmer than ever and Ethan knows it's ridiculous for him to continue to squirm. He can't beat Cal physically but there's something, some words that have been battering his mind since he first found out.

"You want to help?"

"Just tell me how."

"Take it from me," Ethan says. He can hear the desperation in his own voice and hates himself for it. "Just get rid of this… this thing."

"Ethan, I-"

"You can't. I know you can't. Don't you get it, Caleb? You can't help."

"I am going to look after you," Cal says in barely more than a whisper.

Ethan feels his brother's arms slide from their forced embrace to gently rest on either shoulder. It's worse to have Cal holding him gently, worse that his brother's conceded he's something that could break.

"I don't want looking after," Ethan snaps. "I don't want any of this."

Cal begins rubbing his hand up and down Ethan's arm. "I don't want this either."

"Well of course you don't." Ethan pushes Cal's arms away and watches as his brother lets them swing helplessly by his side. "You've never been known to actually care about someone else, have you?"

"I care-"

"Yes, I'm sure you care terribly about who's going to fix your problems once I'm incapacitated."

"That's not fair."

"Oh, I'm sorry, am I not being fair?" Ethan retorts. "Because life's so fair, isn't it? I've done nothing to deserve this, Caleb. I've worked hard. I'm kind, friendly, respectful." As he meets Cal's damp eyes he feels a rush of heat swamp his already aching head. How dare Cal be upset when he's come out of this so fortunate? "I don't mess women around," he continues. "I don't lie. I don't steal from my brother."

"But I do, right?"

"Yes," Ethan says. "You do."

Ethan watches Cal battle with himself. His body's frozen but his face works through a multitude of expressions before finally settling on one Ethan would have never expected.

And slowly, slowly, Cal nods his head. "I know," he says. "It should have been me."

As Cal waits for his brother to respond he hears his own words reverberate in his head. He's been tormented for days with the knowledge that it should have been him, but the guilt intensifies now that he's said it out loud.

He watches Ethan out of the corner of his eye. His bottom lip is trembling again but apart from that his face is blank and Cal has no cues to whether his brother is going to shout or cry. Instead, Ethan slumps to the floor and rests his head in his knees.

"I know you won't believe me," Cal says. "But if I could take it from you, I would. You're the last person who deserves this, Ethan, but I imagine I'm quite high up on the list."

Ethan's shrug isn't enough of a reassurance so when Cal crouches beside him, he's still half expecting to get pushed away.

It's worse when Ethan fails to acknowledge his presence.

"It was the best moment of my life when I thought we were both clear," Cal says quietly. "The worst was when you showed me your test results."

Ethan sniffs but when he raises his head, Cal can see he's still not crying. It would be a miracle how his little brother can hold himself together when he should be falling apart, but Cal knows him well enough to detect the fragility within the calm exterior.

"Mine too," Ethan whispers.

A thought hangs in the air, uninvited; there's worse to come.

Cal manoeuvres so he and his brother are sat side by side on the floor. There's barely a centremetre between their shoulders but it may as well be a chasm. Cal doesn't understand how they've fallen so far from the boys who raced each other on the beach. They've always had ups and down but their grief should be united.

The continuous tick of Ethan's clock makes his head pound. He wonders how it doesn't drive his brother insane, especially now. They should be savouring every second not listening to the countdown.

"I know you're angry at me," Cal says. "And that's okay. Take it out on me, shout at me, hit me. Do whatever you need to. But please don't shut me out, Ethan. I want to be here for you."

Ethan doesn't reply.

"What would Mum say, huh? What would she say if she knew we weren't getting through this together?"

Ethan raises his eyebrows and Cal wonders if they're both deliberating which mum he meant. He shrugs the answer. Either. Both.

"What does it matter?" Ethan snaps. "Matilda and Emilie are both dead."

The harshness from his brother's lips is so unfamiliar that Cal misses a couple of breaths. He wants to cry, to brutally sob and it's nothing to do with the reminder of his mother's deaths. He wants to weep because his gentle little brother has been damaged by his diagnosis and he doesn't know if he'll ever get his Ethan back.

He blinks furiously and stems the tears. He can't cry now, not without undermining his brother's pain. He'll save his breakdown for later, when they've retreated to separate rooms.

"Gone but not forgotten," Cal says. It's an old cliché but he can imagine hearing it in of his mothers' voices.

"Well, I certainly can't forget Emilie!"

"Ethan-"

"You know, I've never understood that anyway," Ethan continues. "Talking about dead people as if they were still here, saying they'd be proud or disappointed, or… How would anyone know? They're dead."

Cal can remember several conversations following their adoptive mum's death where Ethan told him exactly what she would think of his antics, but he chooses not to comment. He's far too distracted by the alien tone to his brother's voice. It sounds as if another person has climbed inside Ethan's body and filled every pore with bitterness.

"Okay then," Cal says. "What about if our results were the other way around. What if I had the gene? What if I was so upset, so angry, that I wouldn't let you help? If I pushed everyone away? And you, you knew that the only thing that could comfort me was having my brother around, having someone who could tell me that whatever happens, whenever it happens, I won't have to fight it on my own. What if you wanted to tell me that, but I wouldn't listen?"

Ethan bristles but Cal decides the lack of an immediate comeback is a positive. He can tell from the creases across his brother's brow that he's considering it, at least.

"Well…" Ethan begins. "Hypothetically, I would have to assume some logic. First of all I would want to work out why you were reluctant to listen."

"Yeah?" Cal's reply is appeased with the realisation that Ethan sounds a bit more like himself. "And why would that be?"

Ethan's silent for such a long time that Cal shakes his head, cross with himself for pushing him too far, for blowing it yet again.

Eventually, Ethan removes his glasses and takes a deep breath. "I think there would be a whole mass of reasons," he says. "You'd find it hard – probably – to be around me because the whole time you'd be imagining what it would feel like if I had it instead of you. You'd be wishing I had it but then you wouldn't be able to look at me because of the guilt for having that thought."

Cal bows his head. "But, I imagine," he says, "you'd be feeling guilty anyway, for being the one who got the all clear. You'd be wishing it on yourself just so that I didn't have to go through it."

Ethan's chin quivers. His eyes flicker to Cal's and Cal can see comprehension dawning on his little brother's face.

"But," Ethan continues, "but you'd be so angry that you can't think clearly. You wouldn't know that's how I felt."

"Yeah, because you – I mean I – wouldn't listen."

"Because it seems so pointless listening when all you can think of is how your whole future has been stripped away. You know that no-one, not even your brother, can change that."

"But your brother can – oh screw this, I can support you through it."

Ethan shakily exhales. "But only if you're always going to be there. I know you usually run, Cal, I'm not going to get used to leaning on you now if you're going to go when I need you the most."

"I promise you, I'm always going to be there."

Ethan stares at him for a moment or two but then hides his face back in his knees. "I can think of the biggest reason, if you had the gene, why you'd be pushing me away."

"Go on."

"You wouldn't want me to see how scared you really were."

Cal can see Ethan's shoulders shuddering. He ignores the ache in his own chest and pulls his little brother close to him. A fleeting glance of Ethan's face shows he has finally succumbed to tears.

Ethan can feel Cal's hand rubbing circles on his back. He can hear his brother murmuring useless words of comfort. He can sense that Cal's crying too but as his face is buried against his brother's chest, it's only the tremble from his arms and the break in his voice that give it away.

Any other time, Ethan would be ashamed of the noises he was making. Today the gasps and the splutters and the high pitched sobs pale into insignificance. He has Huntington's disease and he's going to have to get used to sacrificing his dignity.

Except, now that he's started crying, he doesn't know if he can stop.

"I'm scared, Cal," he weeps.

"I know," Cal soothes.

Ethan's beginning to get uncomfortable but he's not ready to manage without Cal's embrace. He shuffles and his brother does the same, in unison for once, so that they can wrap their arms around each other much more easily.

Ethan almost panics when he realises he can't stop shaking and inevitably his mind slips to the impending disease. He can picture Emilie as clearly as his own reflection and with that comes every twitch, every shudder, every movement she couldn't control. He knows his shivers today aren't a symptom but it's too much of a parallel for him to ignore. It's a taster, a foresight, a warning.

It's terrifying to imagine being shrouded in the worst of the disease.

"I don't- I don't want it," Ethan stutters. "I can't…"

Cal's lips graze his forehead and then he feels his chin being tilted upwards. Somehow, he's surprised to find his brother's face to close to his. Cal's eyes and nose are swollen but Ethan suspects his own are worse.

"Ethan, you're the strongest person I know," Cal says. His voice is thick, as though his throat is flooded with tears. "You can cope with this, I promise."

Ethan shakes his head. Managing to cope with the diagnosis seems as impossible as finding a cure. He feels another tear snake down his cheek but Cal's hand is immediately there, wiping it away. Ethan flinches at the intimate touch and Cal blinks, swiftly removing his hand. He hadn't meant to rebuff the gesture and so gently places his own hand on top of his brother's. Their fingers intertwine and the grip grows stronger.

"You can. But I meant what I said," Cal continues. "I will be with you every step of the way. I'll do whatever you want."

"Just don't go," Ethan begs. "Not this time."

"I won't. I know I've not always given you much reason to believe me but Ethan, honestly, I won't let you down this time."

Ethan shuts his eyes, blocks out Cal's earnest gaze. More than anything he wants to believe in his brother but experience has taught him to have low expectations.

"It won't be easy, Caleb."

"That's why I want to be there for you."

"I meant that you'll find it difficult." Ethan sighs. He doesn't want to say these words but he has to be sure that Cal fully understands what he's committing to. "I'm going to get sick, Cal. You'll have to watch every deterioration. I'll probably be depressed. I'll certainly be physically disabled. I'm going to need help with everything." He pauses to dab at his eyes. "I won't be the brother you recognise now."

Cal nods. A tear drips off his chin. "You'll still be my brother. And I'll be yours. I'm going nowhere, Ethan, I promise."

Ethan's roughly pulled back against his brother and he returns the hug with full vehemence. Nothing's changed yet everything's changed. He's still got Huntington's. He's still going to get ill, going to die painfully and young. But now he has his brother by his side.

And together they can cope.