The day after Tom was killed, I felt mostly numb. Wrapped in a blanket that my best friend, Monica, had draped around my shoulders as I sat on the large corner sofa in the living room, it was as if I was the one who was dead.

I felt nothing. No pain. No anguish. Just this all-consuming numbness that engulfed my whole body. I think, if I had pricked my finger or run a blade across my palm, I wouldn't even have felt the sting.

Just an endless nothing.

At some point, after hours of people coming and going - the headteacher from the school where Tom worked, Tom's sister Tania who'd screamed at me until I'd finally turned my face away from the window and looked directly at her, DI McCain, the police inspector who'd walked mud onto the hallway rug - I'd drifted into the kitchen, the blanket falling free from my shoulders when I saw Tom's coffee mug on the worktop, unwashed since the day before.

It was an ugly cup, some hideously decorated merchandise of one of his favourite bands and I'd always been on at him to get rid of it, but he'd steadfastly refused, declaring that coffee and tea tasted much better in the ugly mug than any other cup.

It was just a cup. A stupid cup. Yet the sight of it made my legs give way underneath me, because all I could think about was how he would never drink from that cup ever again. He was everywhere around me. In the pictures he had hung on the wall, constantly cursing because he was shit at DIY. In the stack of DVD's on the TV unit, that he insisted on keeping even though we watched everything on streaming services. In the sweater he had chucked on the back of the sofa, telling me he'd definitely put it in the laundry later and then left it there for three days. I couldn't have walked anywhere in the house without seeing him, but it was the cup that tipped me over the edge.

Months later, when I'd had to move out because of all the trouble – and because I couldn't keep up the mortgage repayments on my own – the cup came back to haunt me once more when it broke in transit. The handle fell off, a small crack at the base that kept growing and growing until even superglue wouldn't hold it, and I'd cried all over again, clutching the broken cup to my chest as I'd sobbed like I hadn't done in ages. It had felt like a kick to the stomach, hard and violent and unrelenting, until I thought I might be bruised forever.

The truth was, I was still bruised by it all. Broken. Never to be fixed.

As I stared at the Grey now, I couldn't help but think of that stupid bloody cup and how much I'd ached to see him drink from it again, dunking a biscuit in it and then staring forlornly into the tea when half the biscuit dissolved beneath the surface.

'You're actually being serious, aren't you?' I said.

The Grey's expression faltered, his mouth turning down into a frown that I had always thought adorable on Tom's face.

That was it.

That was why I couldn't shake the image of the damn mug from my head. I was looking at the Grey's mouth, remembering what it was like to see Tom sip at his tea.

Remembering what it was like to feel that mouth pressed against mine.

I'd always loved his mouth. The shape of it. The taste of it.

I blinked back my grief and inhaled deep.

'Yes,' he replied. 'Absolutely.'

'Why would a Grey ever need protection? And from who?'

My head was spinning, and I knew I should probably lie down again, but I couldn't. Not with him here. Not with so many questions churning around in my mind.

'From them,' he said. 'From my kind, as you call them.'

The Grey put the gun down on the floor between his legs and leant back, stretching out his arms and resting his wrists on his knees. He was silent for a moment, scratching his thumb nail along the skin on the side of his index finger, seemingly deep in thought.

He didn't look at me when he spoke, adrift in a memory I could see practically tattooed upon his face.

'I never set out to... to kill him. It wasn't planned. Not like it usually is. Some people we take because it's important, because it's pivotal to our plan. Key figures. Your leaders. Some people are smaller cogs in the wheel. Tom was... neither of those things.'

He might as well have reached out and punched me. The effect was the same as a blow to the gut that would have winded me if it wasn't for the fact my body already felt like it had been tossed around in a Spanish bull-run.

'Not important?' I said, clenching my hands into fists in my lap. 'Not important? Fuck you. He was a person. He was alive. He meant something, maybe not to you, but to me and to everyone that loved him. Don't fucking dismiss him like his life was meaningless.'

'I'm trying to tell you that I never meant to kill him, okay?' the Grey said, clearly doing his best to look tormented. 'When you and Tom found me, I was injured badly. I was dying and needed to transition fast. It was the only way to stay alive. I never set out to hurt him or hurt you for that matter. You weren't chosen. You were just... there.'

'Wrong place, wrong time?' I said, sarcastically. 'Could you be any more flippant?'

He winced. 'I'm not trying to be. I'm trying to explain. I was on the run. Three days before I met you and Tom, I'd disconnected from the hive. The central core. I think they knew it was coming, I was being... watched. I never saw anyone, I just knew. I could feel it. That's the way it is with us. You can just sense it, like it's under your skin. When I broke away, they sent the skrycha after me. Sorry, it's not the right way to say it, just the closest to our word for it. I can't say it in this form, it requires...' He looked at me, almost apologetically... 'different anatomy.'

I didn't want to think about that now. About what he was underneath. The idea of this different anatomy made me feel a little sick. 'So, what are they? These skrycha or whatever you call them? Alien police?'

His face clouded as he lowered his voice to a hushed tone, almost as if he thought they – whoever the Hell they were, if they were actually real at all and not something he'd just made up - would hear and come for him. 'The skrycha are similar to assassins. They're sent when there's dissent in the ranks. To wipe it out before it can breed and spread. They can't have that. The hive needs loyalty. Demands loyalty.'

'You're trying to tell me that there are Greys out there that don't go along with the Grand Plan of Taking over the Universe?' I snorted, dismissing the idea.

The Grey scowled, as if offended. 'Every great society has its revolutionaries.'

'One, you're not a great society. The Greys are nothing but one big killing machine. Two, revolutionaries?' I laughed bitterly. 'Is that what you think you are? Some kind of alien Che Guevara? You're no revolutionary. You're a murderer. An animal.'

'Stop saying that!' he said, clearly riled now. 'We're not all the same. We're not!'

I stared at him for a few seconds, seeing the fake indignation in his eyes. Taking another swig of water, I swallowed it down, hoping it could dampen the temper that was rising again, stirring from the depths at the sheer audacity of this creature, who thought he could claim to be nothing but a pawn in a much bigger game. They were all the same. All of them. All twisted, evil creatures. This was why our planet was dying and becoming nothing but a ghost star in the far expanses of space.

'How old are you?' I said, my voice much calmer than I felt. 'And I'm talking Grey years, not Tom's age.'

He frowned, the confusion crinkling his brow and nose. 'What relevance does that have?'

'Let's just say it's curiosity,' I said, shrugging. 'A big failing of the human race, sadly, we can't keep our noses out of other people's business. I just wondered. You're clearly a superior species, right? One that has the power to destroy whole civilisations and whole worlds. So, I'm curious. How old are you? How long does a Grey live?'

'Approximately five of your lifetimes.'

I nodded, like this was old information, which of course, it wasn't. We knew barely anything about them. How could we? When the invasion came, the shockwaves of it had yanked the rug out from under our feet, rocking the foundations of everything we thought we knew – because in our arrogance, we assumed we knew everything – and getting back up again had been something we still hadn't mastered.

'How old are you?'

The Grey hesitated, scratching harder at his finger which was starting to redden angrily. 'I am... not one of the old ones. About one and half of your lifetimes.'

'How long have you been here? Not as Tom, but overall, since the beginning?'

In the corner of the room, the candles flickered, their lazy flames agitated by the air that must have come from a breeze under the doorway, because the Grey hadn't moved an inch. In fact, he looked frozen solid as he stared back at me, immovable, like the marbled centaur in the entrance hall above us. I wondered if it would hurt as much when I hit him, as it had when I'd hit the statue.

'I've been stationed here for about fifty years now,' he replied, holding his index finger to his mouth and sucking on it gently where he'd made the skin sore.

I'd been trying so hard not to be moved by anything he said, but this new revelation, this new horror, almost made me drop the bottle of water in my lap. I wasn't sure if it was possible for the Greys to sweep that metaphorical rug out any further, but this made me glad to be sitting down as it might have brought me to my knees.

Fifty years. Longer than I had been alive. Almost twice as old as Tom had been when he was killed.

'How many?' I asked, aghast. 'How many lives did you take before Tom? How many identities had you stolen by then?'

The Grey rubbed his fingertips over his mouth, the answer almost inaudible that I had to ask him to repeat it. I'd heard it. I knew I had, but I needed him to say it again.

'Six. Six lives.'

'Lucky number seven,' I whispered.

'I'm sorry.'

Two words. Two pathetic, meaningless words that made me so angry, the tears sprang to my eyes again, a scalding heat climbing my throat. I needed desperately to stay calm now. After Tom had gone, anger had replaced the numbness. It had been irrational, a whirling choleric tornado that had made me say and do stupid things which finally broken the thread which had been holding everything together and I couldn't let that happen now. I couldn't unravel. I needed to get this right.

I studied the alien for a moment. 'Tell me something,' I said. 'How does someone who has lived one and half human lifetimes already, fifty years of which were spent on this Earth doing just what you animals do so well, murdering and cloning and being part of the Grand Plan, how do you suddenly turn around and become an extra-terrestrial Che Guevara? How does that work exactly? Do you just wake up one day, sick and tired of living somebody else's life and think well, fuck, I don't think I want to do this anymore?'

The Grey frowned. 'I don't know what you mean?'

'It's quite simple,' I replied, the corners of my mouth twisting into a cruel smile. 'You say you're not like the others. You're different. You're unique. You actually have a heart. Of course, it's a human one that you stole, but you care, damn it. You actually give a shit. The alien equivalent of a bleeding heart, snowflake, liberal! You hate the murdering and the killing. You hate stripping worlds of every last resource. The thought of genocide is starting to make you feel just a little nauseous. How is it you made this startling discovery just three days before you then decided to kill Tom, just because he was in the wrong place at the wrong time?'

'You think I'm lying.'

God, why did he have to look so wronged? He'd killed Tom. He'd killed six others before him and yet for some reason, the idea of being labelled a liar was the one thing that bothered him?

'To be fair,' I said, 'it would make more sense, because that's what you all do, isn't it? You've lied for years. Fifty years in your case. You lie and you pretend, and you kill. There's really not much more to it than that. You really expect me to believe that you suddenly had a change of heart and decided to quit? How do you do that, by the way? Do you have to send in a resignation letter? A face-to-face meeting, perhaps? How does one quit an evil regime of flesh-cloning monsters?'

'I don't remember you ever being this sarcastic.'

'You don't remember me at all,' I said. 'That's what he remembers and he's dead. When are you going to get that?'

The Grey's lips thinned as he bit down on whatever retort he wanted to come back at me with. With a small harrumph of frustration, he climbed to his feet and walked to the stack of water bottles in the corner and tore at the plastic to get inside.

Glancing sideways, I realised he'd left my gun on the floor nearby.

My gun. Mine. My hands itched for it. My rage itched for it.

'You're not going to do it,' he said, quietly, with his back still turned.

He pulled out a bottle of water, his stance very casual, as he unscrewed the cap. When he turned around and raised the bottle to his lips, he was smirking a little – not a Tom thing and it threw me off kilter to see it – before taking a long, steady gulp of water. Whatever nerves or uncertainty had been there before was gone now. Washed away. Like it had never even existed.

'I mean, you could?' he continued. 'You could try and drag your poor bruised and battered body over there. It's not that far. You could try and get to it before me, but even if you could – which, let's face it, is unlikely considering the state you're in - you're not going to.'

I glared at him, feeling every inch of hate welling up inside me again, threatening to pull me under. 'You seem very sure of that,' I said, and I could see that he was. He was so confident; he was practically gleaming with this sense of superiority that prickled the hair on the back of my neck.

'You're not going to kill me, Evie. You would have done it already, just as I would have killed you, if that was what I'd wanted. Whether you like it or not, we need each other.'

Everything was hurting again now, every muscle tensed as I did my best to stay still and not launch myself at his arrogant bastard face.

'Oh, that's right,' I said. 'Your big plan to overthrow your own people. Sure.' I laughed, but it didn't sound like me. It sounded like he had when I'd first woken up. Robotic. Cold. Alien. 'If you honestly think I am going to believe a single thing you promise, I was right, and you really are fucking crazy. You think we don't know what's going on? You made such a mistake leaving Rico alive for us to find him. You should have just killed him and got rid of his stinking, rotting alien corpse. You're planting your own people into our groups. You're infiltrating us, just as you always have. This is what you do! And you expect me to roll out the red carpet and bring you back so you can kill everyone, just like with Lena's group?'

His eyes were flashing bright as he considered what I'd said, holding the rim of the bottle against his mouth. 'I don't know if you've noticed, but Lena's not dead.'

'Unless she's already one of you. Maybe her and Rico were in it together. Maybe one of your kind got to her when Rico had the rest of them killed.'

'I had nothing to do with what happened to Lena's group. I saved her before Rico could kill her. Ask her yourself.'

I rolled my eyes. 'Oh my god, this just gets better and better. Sure, okay, I'll go out there now and ask someone who's probably masquerading as a human whether she's a human or a Grey. That'll work. I'm sure she'll tell me the truth, right?'

He looked so smug then, so unlike Tom even though it was the same face, the same eyes, the same mouth. I wasn't sure how I could ever come to hate that mouth, but I did then. I hated it and I hated him.

'Sure. Why not? Go out there and ask her.' He raised the bottle to gesture at the door. 'Ask her in front of your friend, Jace, whether or not she's like me?'

My face fell as his smirk widened into something horrible. A hint of wickedness that Tom would never have displayed.

I see you. I see what you really are under that skin.

'You can't, can you? Just the same as you can't kill me now, because if you do, you're going to have to tell Jace your dirty little secret. All about your dead husband. All about how you just let him save a Grey. About how you've just sat in this room with me, for the longest time, doing just what exactly? Talking? Reminiscing? Conspiring, maybe?'

Conspiring? Is that what the kids are calling it these days?

'Do you think he's going to be okay with all of that, Evie? Do you?'

Stepping closer, he crouched down to the floor near my feet, leaning forward a little as he watched me, his face triumphant. His hand was close to my leg and I couldn't stop looking at it, terrified that he would touch me, and I wouldn't be able to stop screaming.

'Do you know what I think?' he said. 'I think you're going to bury that little secret of yours right back in the grave, where it's been these past two years, because telling Jace would destroy everything, wouldn't it? Do you think he would trust you ever again? Would the rest of them? You've lied to them, Evie. You could have told them about me already, but you didn't. You saw me and thought you could keep lying to them. Try and kill me then. Tell him everything. Tell him the truth about what happened. Let's see how well that goes for you, shall we?'