Internal Combustion.

They had sat in silence for a eight, almost nine, minutes. Gwen knew she had to give Arthur room, give him silence to fill with thoughts and internal reasoning, but it had grown uncomfortable. It was a Saturday tomorrow, so she didn't have to worry about getting up early for work, and would give him all the time he needed but the comfort she'd felt before had definitely changed, mutated into something large and full. It spilled over with the twists and knots in the air and in her stomach. It had never felt like that before.

'Arthur,' she had just started to say when he interrupted her with his question.

'What was your news?'

'Oh.'

She was thrown by the sudden subject change, but the news she had made her smile in spite of everything.

Arthur quirked a brow at her expression. 'What?'

She bit her bottom lip and knew she looked ridiculous with her cheek scooping smile, so controlled her smile and with the calmest and clearest voice she could manage said, 'Lance proposed.'

'What?'

'Last night after his shift he took me to this restaurant in Piccadilly, the Savini at Criterion, and it was beautiful,' she rambled. Arthur's stare was shocked, delighted, sad, but she ignored the latter and remembered the night before. Lance had pulled the chair back for her, wore his best suit, and kept blushing. His smooth talking became more stunted at times, a little off, and it had been adorable and endearing and then he'd fallen quiet. They'd stared at each other over the candles for god knows how long and then he reached into his pocket, came over to her side and bent down onto one knee. The other people in the restaurant had whispered to each other excitedly and turned their heads, and Gwen's head had felt like the candlelight. Warm, bright, perfect. 'One of the most beautiful places I've ever been. At first he said it was to celebrate our eight month anniversary but then he proposed.'

'What did you say?'

'Yes, of course,' she said, her big smile back. Lance's face was etched into her mind when she'd said yes. He'd kissed her and swept her up into a hug and people had applauded and she had fallen in love with him all over again. They couldn't stop laughing the whole night. Something about the Thursday had felt different, as if the air were full of hope. Her feeling had been right. 'His cousin is flying in from Madrid with the engagement ring tonight.'

'Congratulations, Gwen,' Arthur said and gave her a sincere, toothy smile.

'Thank you.' She couldn't believe it but she managed a wider smile of her own. 'Guinevere du Lac. It sounds quite good, doesn't it?'

Arthur nodded. 'It does.'

Someone knocked at the door.

'Is that Lance?' he asked.

Gwen shook her head. His shift wasn't over until 4am the next morning.

'Hang on a second,' she said, slipped off the high kitchen stool and went to answer. When she opened the door Merlin stared at her. He looked better, exhausted with too-hollow cheeks, unkept stubble and slumped shoulders, but better than he had the day before. 'Merlin, what are you doing here? Shouldn't you be resting?'

'Is Arthur here?' he asked her quietly, clearly.

'Yes.'

She remained in the doorway, didn't invite him in, and thought over the options. They had the strangest relationship she'd ever known, but one of the strongest. They'd work it out. 'Wait for a second?'

He seemed to think about it, then agreed. 'Sure.'

She left the door open and hurried back to Arthur in the kitchen. His eyes were dark.

'No,' was all he said and returned to the cauliflower, stirring at it pointlessly.

'Arthur,' she started but he killed her next words with a look.

'I can't,' he said, 'not now.'

'Okay.'

She went back to the door. Merlin repeatedly tapped the front of his right shoe against the bottom of a flower pot beside the steps. When he heard her he looked up, eyes wide with something unpleasant, but it fell away instantly.

'I'm sorry, Merlin, he says he can't talk right now,' she recounted in her softest voice. 'I'm sure you can try again tomorrow. Call him, maybe?'

'No, no, I can't call. He needs to know,' he said and the strain in his voice tightened around his eyes. 'It can't wait.'

Gwen leaned against the doorframe, hating how he looked at her with the depressed panic in his eyes. She pressed her lips together and told him, 'He won't come, Merlin.'

He winced a little when she did and then his expression hardened. 'Then you have to tell him. I'm sorry, Gwen, but he has to know, and unless you want me to storm in there-'

'You can tell me,' she stopped him and kept her voice soft. 'What's wrong?'

'It's Morgana,' he began and paused, eyes dropped down as he worked through his words. When he looked up the tight eyes and strained voice were gone, replaced with a strength and practicality that scared her. That made her want to pull him into a hug and never let go. She swallowed and braced herself when he continued. 'She found Mordred and went to him when everything with Aredian happened. She saved him, saved my life because she did, but Nimueh stabbed her. She fell.'

Gwen frowned at him, her hands and feet cold with a spreading numb tingle. Another silence stretched and she pressed her eyes and head into it.

'Morgana's dead?'

'Yes.'

'Oh my god,' she said brought her cold hand up to cover her mouth. Everything was slower, duller, and Merlin watched her silently, stood in the centre of it all. 'His father died less than a year ago. Now Morgana?'

Merlin's brows pinched together and his hard look slipped. 'I'm so sorry. I wanted to tell him myself. I should have, I'm sorry Gwen. Let me in, I'll tell him myself, okay?'

'No, Merlin, it's alright,' Gwen said and put her hand out against his chest when he stepped forward. 'With the mood he's in, with whatever happened between you, it'd be better for me to tell him. Thank you.'

'Sorry,' he said and stepped back. He made to turn away but she stopped him a hand on his arm.

'Merlin.'

'Yeah?'

She wanted to tell him it would all work out, that they'd get through this, that Arthur would forgive him for whatever he'd done, that they'd go on at the Yard like before Christmas when things had been straight forward. She wanted to tell him that the magic, Old Religion, Mordred, that none of it changed how Arthur felt, how they all felt. She could see how those words would drain the darkness from his eyes, maybe turn the sharpness in his expression soft.

'Gwen?' he said in her silence. She let go of his arm and wrapped it around the door handle.

'Nothing.'

Merlin frowned but nodded, tucked his hands into his coat pocket, and headed down the front pathway. She saw four of his steps and on what should have been the fifth he was gone. The walkway that ran along the front of the houses was deserted, the wind turned cold as it blew over the Thames, and the pollution-lighted night sky droned with a passing aeroplane.

.

.

.

Mordred stretched out in the bed and stretched open his mouth with a yawn. He rolled over and slammed his hand down on the alarm clock to shut it up. Its rings echoed in his ears a little and made the air taste bitter. When he heard the sleepy mumble behind him the bitterness disappeared. He turned over until his nose almost touched Merlin's.

'Merlin,' he whispered, and the man groaned at him before nuzzling his face into the his pillow. 'Merlin, it's seven.'

Mordred pulled his hand out from under the heat of the shared duvet and brushed back some of the dark hair that rested over his cheekbone. No groan, no words, just level and deep breaths.

'You can't sleep through your first day back on the clock,' Mordred told him gently. He could hear the smile in his voice when he said it. 'You've had a whole week to hide.'

He brushed back more hair and Merlin groaned at him then rolled over to put his back to Mordred. He let out a sigh and propped himself up onto his right elbow. Dipping his head down next to Merlin's ear he blew against it.

'Stop it,' Merlin mumbled to him and covered his ear with a hand.

'You have to get up,' he said. 'I'll stop when you're out of bed.'

Silence. Mordred's smile widened.

'Don't make me use magic.'

Merlin craned his head back to glare at him. 'You wouldn't.'

His voice was heavy and low with sleep and Mordred swallowed the tightness in his throat.

'I would,' he said and let the warmth blow out of his left hand. It was numb as ice the next second and he quickly tucked it under the covers and found Merlin's warm hip. When Mordred pressed the cold hand against his exposed skin, to then tuck it up under his t-shirt, he let out a high-pitched yelp and tried to get away.

Mordred pulled Merlin back against him and ran the cold hand up over his chest. He laughed against Merlin's ear as he squirmed but Merlin managed to turn over and grab his hands to pin them either side of his head.

His breathing hitched and Mordred held his breath as he looked up at Merlin's smiling face. The laughter and smile died away and they looked at each other like that for a minute, maybe two, three, he didn't care and couldn't keep track. Mordred was uncomfortably aware of the warmth, the pressure of Merlin's hands around his wrists, his knees on either side of his hips. It threw his head back into that hotel, the anger and the kiss, the fire and Aglain's blood.

'We have to get ready,' Mordred told him in a small voice. Merlin blinked at him and for a moment Mordred could have sworn he leaned closer, but he climbed off and got to his feet before he could be sure.

Merlin grabbed some clothes from his wardrobe and turned back to ask, 'Can you give me a lift?'

He nodded and Merlin went to change in the bathroom, locking the door behind him. He grabbed his own clothes out of the suitcase he'd haphazardly packed almost a week before. Merlin had gone with him to the Islington flat, the place he'd called a home with Morgana, the place he'd lied and pretended to still be that monster. He'd packed up his clothes, essentials, documents, whatever else he thought could be relevant, and let Merlin Vanish with it back to Notting Hill. He'd then driven his motorbike through central and parked it in front of the park.

Twenty minutes later and they'd both showered, dressed, and packed their bags. Mordred still found it hard to eat, and Merlin was even worse, but they had water, coffee, an apple each. It felt like some strange recovery or rehabilitation, which it was, but it was something else undefinable. Mordred buttoned up his coat against the cooler August wind and waited next to his bike. It was second hand, loved, ridden to a mileage of around 1000, and marked his new start from what had happened the year before.

The Yamaha YBR 125 had cost a little over a thousand pounds and felt simple, down to earth, honest. Mordred moved his helmet from one hand to the next as he waited beside it. After a minute or two Merlin emerged from the white building and stepped down past the pretentious pillars. He carried the other helmet Mordred had bought for him last Wednesday when Merlin had gone in for his interview, interrogation, whatever Scotland Yard's internal affairs investigators wanted to call it.

They'd decided not to hold a misconduct hearing and let Merlin continue with a small leave of absence after the attack. Suspensions had been lifted, the Commissioner had released a statement clarifying the Met's commitment to justice and perseverance in the face of adversity and so on. Last week had been difficult, least of all because of the cold shoulder he received from Arthur's entire murder investigation team. A cold shoulder Merlin had also received.

Morgana had been declared 'missing' and he now had a meeting with Commander Richard Marten, head of the Intelligence Command, at 8am sharp.

Mordred pushed the helmet down over his head once Merlin crossed the street and swung his leg over the bike. He tightened the strap under his chin and flipped down the visor. It channelled his sight, secured his mind against the sometimes overwhelming details of the world around him. Merlin had described to him the colours he saw, and while his own magic didn't translate into the world like that he understood it. Sounds had tastes to him, smells had sounds, atmospheres had texture.

He turned the key, kicked the side stand up with his heel and pushed down on the kickstarter three times before the engine sparked into life. The sound was metallic, organic, and Mordred could feel the air mix with fuel, feel the fire that forced up piston after piston. He kept the transmission in neutral, engine warming up with a reassuring vibrating purr, and grabbed onto the handles when Merlin climbed on behind him. Mordred half expected him to use the passenger grab bars so when Merlin slipped his arms around his waist securely his heart skipped an irritating beat.

'Ready?' he asked through the helmet and partly turned his head back.

'Yeah,' Merlin said and moved a little closer against him. He pulled on the clutch, shifted into first gear, and turned into the road. A mostly empty backpack stood between him and Merlin, but, squished by Merlin's chest, the slight pressure made him feel more secure.

They made it to the yard by 7:50-ish according to Mordred's analogue watch. He parked the bike and let Merlin climb off before he joined him as they headed to the main entrance. The ride had been peaceful, fun, exhilarating, and Mordred was tempted, like always, to just stay on it and ride forever. Merlin's warmth stopped him this time, just as the thought of going back to him in the evenings the whole of last week had kept him in London, kept him sane.

'Go on ahead,' Merlin told him and paused at the gate of the private car park.

Mordred looked at him and put a hand on his shoulder. 'You're okay.'

Merlin nodded and gave him a small smile. He struggled to pull his hand back, but forced himself to walk away after twenty-three seconds. Time had gained a strange specificity in his head since he got back from wherever Nimueh had kept him. Mordred understood his own mind enough to know that was because he'd been so painfully unaware in the cave. Now time was his anchor.

He unbuttoned his coat and stepped into the lift. It was in the latter half of 7:50-ish. Running late for the meeting wasn't a great start, not that he was entirely eager to go to it. The lift filled up with people quickly, and he clenched his jaws when it took on board its last few passengers.

'You should be happy that Kilgharrah is making you SIO of an investigation so soon,' Gwaine told Arthur with his Irish accent. 'Cheer up, mate.'

'Sleep is for the dead, remember?' Leon added with a grin and friendly nudge. That was when he spotted Mordred and the smile blinked away. 'DC Leir.'

Mordred didn't respond with any words, just nodded, but it wasn't enough. Arthur had trained his eyes on him. They drifted downwards and hardened at something on his chest. Mordred frowned at the strange look.

'That's Merlin's tie,' Arthur said after the pause. He looked down and mentally swore, then swore at himself for swearing in the first place. Why should he feel bad about it? Why should he be so concerned about how Arthur felt about him? He'd made it clear that he didn't want a thing to do with him from the very start, which was fair enough, but the way he'd cut off Merlin for the last week was something else entirely. 'Why are you wearing his tie?

'Arthur,' Gwaine warned lowly, but the lift had only just stopped at its first floor. People left, came in, they were still packed up close and hot.

'It's not what you think,' Mordred said calmly. It was true. He knew what Arthur was probably thinking, he wished it was the case, and he was almost happy in a twisted way that he thought it. The most he and Merlin had done was cuddle, and while he wanted more, he knew Merlin didn't. Not yet or not ever. Mordred couldn't decipher him. He wanted to know to the point of bluntly asking, but the answer he might get terrified him. So, he hadn't asked and wouldn't. Not until they'd both had more time. Until they'd both been anchored a little longer.

'No? Then what is it?' Arthur challenged. The other people in the lift watched the renowned DS Pendragon with furtive glances. 'You know, don't you?'

Mordred kept his mouth shut. Only three more floors and he could get out of this bad situation.

Arthur forced his way closer. 'Of course you do. That's why he let you back into his life. What's the plan this time, Mordred?'

'There's no plan, Arthur.'

The doors opened again and Gwaine tried to pull Arthur out by his arm.

'There always is with you,' Arthur said, his expression sharp and lethal, eyes daring him to do something.

The air was still, hot, hushed. Mordred stared into Arthur's challenge. 'What's your plan, Arthur? Going to ignore him forever? At least I didn't turn my back on him when I remembered.'

Arthur lunged at him. Mordred jerked back a little but Gwaine grabbed him around the waist and pulled him back, someone shouted out his name and called out 'What's going on?' then the lift doors slid shut again. Mordred relaxed his clenched fists and took a calming breath, ignoring the eyes that pressed into him. Two floors later and it was 8:00-ish. Mordred walked to the Commander's office with determined speed and knocked on the door. He stepped inside and Commander Marten, mid-forties, told him to take a seat.

'So,' the Commander started. Mordred had dropped his bag down next to the chair and waited for a scolding, firing, whatever. His return had received mixed reviews, to put it mildly. 'You'll be receiving a commendation. November, in all likelihood.'

Mordred frowned. 'Oh.'

The commander grinned at him. 'Not what you were expecting to hear? Your associations and past digressions are a matter for gossip only, Mordred. Your performance has been exemplary and that's what matters. I've got more news than that, though. There's a new position available and I need to know if you still want to remain in the Intelligence Command.'

'What's the position?'

'You know I can't tell you that until you decide. Remain with Intelligence, or transfer back to Homicide and Serious Crime. Its up to you, Mordred. Last week was mostly paper work, bureaucracy, this is when we get your ball rolling again, so to speak.'

'I need to decide now, don't I?'

'Yes.'

'I'd like to remain with the Intelligence Command.'

'If you take up the new position you'll liaison with the Trident Command. Heard of Operation Kestrel?'

'Yes, sir. It's an initiative launched against gun and knife crime last December.'

'Good. You'll remain a part of Intelligence but function within Trident. This position will build on the skills you gained while undercover with Old Religion,' Commander Martin said and paused as if expecting him to react in some way. Aglain's death had shaken the Command, he knew that, but with what Nimueh had done to him, with what had happened and not happened in the two weeks since he watched his supervisor die, Mordred found it hard to feel anything definitive about it. 'While you were in danger then, it was a relatively short if integral role.'

'And this position?'

'You would need to immerse yourself in the gang environment for an extended period.'

Mordred nodded. 'Weeks?'

'Months,' Marten said. 'I wouldn't be asking if you hadn't proven yourself capable. You're a fighter, Mordred. We need more officers like you in the Met.'

He narrowed his eyes at the Commander. They must be desperate if he was layering such heavy sweet compliments onto the conversation. In fact they did that a lot with him. A commendation, discussing his skill set, his strength, and then they talked about how he went insane, how he obsessed over Merlin, how he came from nothing and that's where he belonged. Mordred had never experienced as much external or internal whiplash before in his life. He'd never had to kill anyone before in his life. The thought made him frown. That first night undercover the first time, he'd had no choice, he'd done what he'd had to, but there was no undoing it. He was a killer because of it. What would happen the second time?

'I'll be meeting DCS Southers, head of the Trident Command, this afternoon and can confirm your involvement in the Operation then,' Marten said. 'You'd begin immersion within the next two weeks. What should I tell him?'

Mordred ran his thumb across the fabric of his trousers. The office atmosphere was peaceful, boring, safe. The magic was overwhelming and exhilarating even in that environment, but it was different now. Merlin was in his head, a warmth in his chest, and he wanted to do something with that. He was good at lying, at surviving, and Morgana had ranted on to him about how important Trident was for the future of London. How they saved the lives of kids and teenagers 'who deserved an escape, a second chance' as she had put it.

'Tell him I'm willing to liaison with his Command,' Mordred said.

'Perfect. I'll have Will take you to their offices in South London.'

'I can go myself.'

'I'm afraid not. Its address is sensitive information. Your first few visits will require an escort.'

Mordred resisted the urge to sigh. 'The escort being Will?'

'DC William Cormack, yes,' Marten said with a close-lipped smile. 'He's a good lad. You two should get along fine.'

'He's in the CID?'

'In the same capacity that you are, or were, yes. I'll give him a call, and he can take you there at,' Marten paused and checked his watch, 'let's say half past. You don't have any other urgent business at the Yard do you?'

'No, sir.'

'That's settled, then. He'll meet you out front. I look forward to seeing where you go with your career, Mordred,' Commander Marten said and stood. He offered out his hand which Mordred shook before he grabbed his bag and headed to the door.

He pulled it open and looked back. 'Thank you, Commander.'

'Keep up the good work, Mordred.'

When he pulled the door shut he took several breaths before checking his watch. It was 8:20-ish. They weren't wasting any time. He hooked the other arm of his backpack over his shoulder and made his way back to the lift.

He pushed down on the ground floor button. Merlin?

Yeah?

I don't know if I'll be here to give you a ride back tonight. Will you be okay?

Magic, remember?

Oh, right, I forgot. Don't know how I forgot actually. I'm talking to you with it now. Thinking to you is more accurate, I suppose.

Where are you going?

Don't know yet. Confidential. Although you'll probably know when I do.

Who needs the privacy anyway?

Mordred smiled to himself and turned down their connection when he reached the Yard's entrance lobby. It was hard to figure out, but he'd realised it wasn't so much a case of cutting himself off from Merlin. It was more like turning down the volume or pressing mute, which suited him fine. He wondered if Merlin knew about what had happened with Arthur, if he knew how he had felt that morning. If he knew what he was thinking. No, that was crazy and paranoid. He couldn't hear Merlin's thoughts unless Merlin explicitly let him hear them. Why would it work any differently in the other direction?

'DC Leir?' someone asked when Mordred stepped outside. He turned his head to the right.

'DC William Cormack?' Mordred asked in return. The man nodded and surveyed him as Mordred did the same. He had startling clear eyes, a strong jaw, and carried bulky strength under his clothes. The soft fabric of his jumper seemed to warm his otherwise strong demeanour.

'You can call me Will,' he said and they shook hands. 'What did old Marten tell you?'

'That you're my escort to the relevant office in south London. Is it Intelligence or Trident owned?'

'Bit of both, I think. I'm a lot more than your escort too, by the way. I'm the closest thing you're gonna have to a partner,' he continued. 'Anyway, it's pretty straight forward to get to so won't take too long.'

'Don't suppose I can take my bike there?'

'Motorbike?'

'Yeah.'

He pursed his lips a little with thought. 'Not unless you let me drive.'

'Know how?'

'My foster dad was a mechanic and loved his bikes. I'd say I'm pretty good,' he said and shrugged one shoulder. Mordred's attention doubled when he said 'foster' and he simultaneously felt a strange connection and self-imposed estrangement from the man. 'Rode my first when I was fourteen, a Honda CB 50, a relic if I've ever seen one. What's the model?'

Mordred led him to the car park and let him circle it. DC Cormack, Will, figured he'd get the hang of it without much trouble and, if Mordred was alright with it, would happily take them to 'HQ' on it. Mordred agreed, comforted by his secret resource in case anything went wrong, and unclipped the two helmets from the bike's frame. He threw one to Will, who caught it easily, then gave him the key.

'What is it you do exactly?'

'Can't tell you that until you sign all the right forms and tick all the right boxes,' he told him with a grin. 'I can tell you that this shit is serious, you'll probably get shot at some point, and you're gonna have to let loose a little on the etiquette.'

'Anything else?'

'It's a boat load of fun,' he added then climbed onto the bike and put on the helmet Merlin had used only half an hour earlier. 'In a life threatening, dead serious sort of way. Come on, we haven't got all day.'

Mordred positioned himself on the seat, hands closed around the passenger bars. It was uncomfortable and worrying to have someone else take the lead on his bike, but DC Cormack seemed to know what he was doing. In fact, he seemed like a nice guy. A nice, sane and non-magic using detective. He started the engine which rumbled beneath Mordred and they drove out of the car park.

Thoughts rumbled out in time with the thrumming, sputtering engine. He'd be undercover for months, with Merlin for months, in London for months, he'd have a partner for months. A bubble of excitement and terror blew up in his stomach. Mordred grinned with the mixture and imagined that it was what internal combustion felt like. Air and fuel shoved together, a spark, and boom. Excitement and terror. He was combusting and it felt amazing.