I'd been following him for about twenty minutes now as he followed the two girls who walked briskly along the towpath about forty metres in front of him.

He was keeping it casual, just another guy on his way home, backpack slung over his right shoulder and one ear bud intact as the white wire coiled down his chest and disappeared inside his jacket. He'd made a couple of calls on his mobile. He'd kept a respectful distance. Not too close. Not too fast.

But I knew he was following them. The calls he'd made were fake. The iPod hidden inside his jacket was mute. There was nothing remotely casual about his journey. And the reason I knew this was because I knew who he was. He had become something of a dark celebrity around here. The Regent's Canal Rapist had struck twelve times already. Eight rapes and four indecent assaults and here he was about to strike another notch on his filthy urban bedpost. Unfortunately for him, he wasn't the only hunter who stalked this route.

The canal, with its oozing black waters, darkened tunnels and narrow towpaths, had become a favourite hunting ground of mine. Of course, you couldn't kill too many down here because who knew where the bodies would end up once the canal had sucked them into its deadly cold embrace, but it was a great place to start if you wanted to find those who wouldn't be missed. Vagrants, prostitutes, dealers and thieves were rife and in the shadows was where they carried out their business. Foolishly, they believed the shadows would harbour them from prying eyes, but my eyes could penetrate the darkest of dank, dirty corners and my sensitive nose could detect where my eyes couldn't.

That's how I had found him, this infamous beast, this vile predator who had invaded the scene of one of my recent kills, unaware of my hiding place in the bushes where I was finishing off Ezra or Esme or whatever the hell she had said her name was. It hadn't seemed important at the time as I'd fallen upon her and buried my head in her neck and pressed my hand down firmly on her mouth, muting her screams as she'd clawed desperately at my back. But as I had sucked voraciously on the open wound in her throat, I had heard desperate little hisses of pleasure and for a moment, I wondered whether I was making that sound, revelling in the warmth of the blood as it filled my mouth. With Ezra or Esme now staring upwards with her dead eyes, I had pulled away from my feed and peered through the thick leaves and there he was, leaning against the wall with one hand, his trousers around his knees and furiously pumping away at his erection with his other hand. A thin sheen of sweat covered his forehead despite the chill of the winter air and his teeth were gritted in a skeletal grimace as he worked himself harder and harder, faster and faster until finally he gasped out loud and shot his load over the old brickwork.

I'd grinned, realising just how easy this one would be. I could have taken him and tossed him in the canal with Ezra-Esme and been done with them both. Fortunately for him, just as I began to creep forward, stepping lightly over the woman's limp body, voices from further down the towpath had him yanking up his trousers and scuttling up the steps towards the road.

I knew it wasn't the last I'd see of him. His scent marked various places along the canal walkways so I knew he was a frequent visitor here. And when I saw the newspaper stand the next night, the Regent's Canal Rapist's latest attack emblazoned in bold black letters, I realised it was him and knew I just had to have him.

His latest victim, a girl in her early twenties out for an evening jog, had thrown herself into the canal to stop him from raping her. Eyeing the waters as I stalked him now, I vowed silently that I would throw him in there too, but only after I had seen the terror in his eyes as I ripped out his throat. I had kept well back, hugging the shadows and avoiding his detection as he casually glanced back to see if anyone followed, but luckily for him, and for me it seemed, any that had walked this route had veered off some time before.

It wasn't long before one of the girls also turned and headed up some steps, after saying goodbye to her friend with a brief hug while the other stayed on the towpath, picking up the pace now that she was alone. It never ceased to amaze me how foolish people could be, blindly walking the path of danger as if they were untouchable. Because of course, the bad things only ever happened to others, right?

The gap between them had closed slightly, due to her stopping to say her farewells and despite her speed now, he was drawing closer by the second but then so was I. My breath was quickening with each light step that I took, the need to feel his body under mine like a fire raging through my veins and no doubt he was feeling the same as he closed in on his prey. We were nearing the Kingsland Road Bridge and instinctively I knew this was his chance, just as it was mine. I couldn't risk letting him reach her, couldn't risk letting her screams alert anyone because he was mine and no one was going to take him from me.

"Excuse me?" I called out, stepping out into the thin light cast from a next-to-useless streetlamp.

The man quickly looked back to see me standing there, before turning back in the direction of the girl. She was almost at the bridge now.

"Please can you help?" I was channelling the old Megan again. Needy. Weak. Vulnerable.

I could see the man was hesitant to stop. He didn't want to lose his prey but he slowed anyway and looked my way again, weighing up what he might lose against what he might gain from helping this girl who was all on her own on the dimly lit towpath. I took a few wary steps towards him.

"Sorry," I stammered. "It's just I'm trying to get to Haggerston Station, do you know if it's nearby?"

"Yeah," the man smiled and stopped. I'd clearly won in the Who Should I Violate Next stakes. "It's just past the next bridge." He pointed in the direction of the girl, who had cleared the bridge now and was disappearing up the steps on the other side.

A small thrill shot through me, raising goose bumps on my skin. We'd passed Haggerston Bridge already, the sound of a passing train clacking along the tracks overhead helping to mask the sound of my footsteps.

"Oh great," I smiled shyly, inching towards him. "Thank you."

"You're welcome," he replied and began to walk towards the bridge again, his pace noticeably slower than before. As he reached the edge of the dark confines of the tunnel, he stopped again, withdrawing his iPod from his inside jacket pocket and pretending to fiddle with the device. I fought the urge to giggle as I drew closer, but my hunger won out. I was aching for him and exhilarated by how close I was to taking him.

He sidestepped to the left to let me pass and as I did so, embracing the darkness of the tunnel and feeling the hair on the back of my neck prickle with excitement, the air shifted behind me and I knew he was moving to attack. When his fingers grasped my hair roughly, I faked a yelp and let him whirl me around until my back hit the wall of the tunnel. Quickly he slammed a hand over my mouth and pressed his body up against mine, his firmness evident through the jersey fabric of his sweatpants as he crushed his groin against my stomach. I could feel his hot breath on my skin as he assessed his prize, his eyes running lasciviously over my face. His blonde hair was cropped short and he was clean shaven, strangely well-groomed for such a beast but as experience had taught me, the demons come in all guises. This one smelt of washing powder and chewing gum.

The hand that had grabbed my hair was trailing down my chest, seeking out the curve of my breast which he squeezed hard and in return my hand, which I had pushed against his shoulder, travelled up to his neck and I couldn't prevent the giggle from bubbling out at the feel of his carotid artery pulsing under my palm. His eyes clouded with confusion and he released the pressure on my mouth.

"It's amazing how these brisk evening walks can get the blood pumping through the veins, isn't it?" I breathed; shifting against him and making him gasp and pull back abruptly. "What's the matter, honey? No longer interested when your date isn't screaming and helpless?"

"What the fuck?" he cried. "What is this?"

"This, I believe, is what you call divine retribution," I said and grinned, giving him a flash of my elongated incisors.

I could have let him run. The thought of chasing him along the towpath, of taking up the hunt, excited me almost as much as the thought of taking him here and now but I knew that the white noise that infested my skull needed to be satiated. It had waited long enough to be fed and I needed to bring this to a close just in case anyone happened to wander down this end of the canal. He got as far as the tunnel's edge before I yanked him back and he stumbled, losing his footing and slipping on the wet pavement slabs. As he tumbled to the ground, his forehead connected with the wall, the impact breaking the skin and I was on him before the scent of his blood even reached my nose, slicking my tongue over the graze as he struggled beneath me.

He was physically fit and athletically built and I knew his victims had never stood a chance against him. Strong and able he might have been, but was panicking, weakened by the terrible realisation that he was the one being attacked and not just by anyone, but by a monster; a make-believe monster who belonged in a book or a movie, not here on the darkened towpath of a London canal.

Straddling him and trapping his arms underneath my knees, I pushed his cheek into the rough stone and moaned when I saw the vein protruding from his neck as he strained against my hold. I moved my mouth close to his ear.

"This not doing it for you, sweetheart?" I murmured. "Pity, because I am so hot for what you've got right now." I nuzzled the warm skin of his neck and he flailed weakly.

I revelled in every second. The sound of his breath wheezing out in heavy, terrified gasps. The slight resistance of his flesh as my teeth pierced his throat. The way his body stiffened beneath mine. The hot rush of blood over my lips. The way his skin tore as I furiously devoured him. That sick, squelchy sound of my mouth sucking harder and harder. The way his feet kicked out frantically, desperate to connect and dislodge me.

Every part of me was buzzing with the most delicious sensation that powered through my veins and tingled across my skin. I didn't want it to ever stop. But finally and reluctantly, it had to be said, I rolled off him and flopped down onto my back beside his still body, my mouth open in silent ecstasy, still feeling the waves of pleasure rock me. I was so stunned by it, that when he rolled onto his front and began to slowly, painfully crawl away, barely able to lift his body off the ground, I just lay there for a moment, watching him claw his way along the towpath, his fingernails tearing as he dug desperately into the hard, unyielding stone.

Sighing, I pulled myself up onto all fours and he slumped forward with a gargled sob as I crawled, spider-like up his body until I was clutching his back. Tears, snot and dirt stained his face and the stench of his blood mixed with the smell of detergent and minty gum. Soon he would smell of nothing but dank water and canal slime.

Wrenching his head back, I slammed it against the ground, knowing that I wouldn't be able to sustain another hit of his blood, knowing that one more bite would render me immobile, lost in the hazy ecstasy of the kill and knowing that the longer I stayed here, the greater the risk of being seen. Thinking of how he had clutched at my breast, I slammed it twice more hearing the skull crack and soften under my fingers.

Sitting back on my haunches, I watched numbly as the blood pooled out from his crushed skull and seeped into the cracks between the slabs.

"Feel better for that?" a voice said and I looked up to see Harper standing by the entrance to the tunnel, casually leaning against the wall with his arms folded across his chest and his legs crossed at the ankles. His expression was blank but his emerald eyes were fixed sharply on me as if he were not just looking at me, but intruding on what was going on inside my head. Frowning, my bottom lip protruding in a sullen scowl, I stood up and rolled the body towards the edge of the towpath, hooking my foot underneath it and pushing it into the dark, sludgy water. Its frozen, petrified features looked back at me in silent stare as it was sucked under, the water hungrily devouring what I hadn't and I hoped that it would never be found, that the reeds would entangle it in the depths, entrapping it in the darkness forever. After all, it was only what it had deserved.

Turning, I removed the zip-up hoody that I'd borrowed from Garrick's clothing stash and wiped up the excess blood until it was just a darkened stain on the stone and tossed the hoody into the water, watching it bob on the surface for a short distance before it too went under.

Stomping past Harper, barely glancing in his direction as I did so, I headed towards the steps where I had seen the girl exit up to Kingsland Road but he grabbed my arm before I could make my get-a-way, forcing me to face him. I glared obstinately at him.

"Are you done?" he asked, raising an eyebrow and I knew he wasn't referring to this night's hunt.

For four nights now he had been my unofficial chaperone as I had stalked the streets, alleyways and darkened corners feeding my hunger with anyone unfortunate enough to be loitering in the shadows. For four nights now, he had watched, like some twisted voyeur as I hunted and fed. For four nights, he had watched and said nothing.

"If you'd rather be home tucked up in bed, then be my guest. I won't stop you," I sneered.

But he wasn't about to walk away, just as he had staunchly refused to let me hunt on my own, shadowing my every step each night whether I wanted him there or not.

"I've humoured this long enough. It's time to stop," he insisted, his grip on my arm tightening.

"I'm hungry," I argued, yanking myself out of his grasp and quickly mounting the steps, hearing his loud exasperated sigh follow me up.

It was close to midnight and I ignored the intrusive stares of the odd passer-by who couldn't help but look at this girl who walked the streets at night without a coat or jacket. Affectionately known as the Pho Mile because of all the Vietnamese restaurants lining the street, Kingsland Road was the epitome of London cool, with the skinny jean hipster brigade ruling the clubs, galleries and bars and of course, as usual I stuck out like a sore thumb. I had the skinny jeans but with my dishevelled hair and crumpled stained t-shirt, I was anything but cool. I carried on regardless knowing that Harper was close behind. My eyes were automatically scanning the street as I walked, darting in every direction, eyeing up each potential victim. There was always ample supply, especially on these streets.

"What about her?" Harper said, easily catching up to my side and motioning towards a young woman standing outside a small indie club. "Or maybe him? I'd bet you'd enjoy him." He gestured towards a guy walking towards us, guitar case in hand and hair swept over his eyes.

"Don't be ridiculous," I uttered through gritted teeth.

"Why not? They all taste the same, Megan. One is just the same as any other. Or do you prefer them a little dirtier? Or a bit more of a challenge maybe?"

"I'm not going to take just anyone, am I?"

"Oh, aren't we a fussy eater, these days? I never realised you had developed such discerning tastes."

I turned on him, furious and irritated by his presence. "Why can't you just leave me the fuck alone? Do you enjoy tormenting me? Actually, wait, I already know the answer to that."

His eyes narrowed. "You think I'm here to enjoy myself? I'm here to keep an eye on you, because right now all you can think about is feeding and you're going to wind up getting yourself killed in the process."

"I told you, I'm hungry." The need inside me was burning again and I was painfully aware of too many warm, human bodies all around me, their hearts beating like little hypnotic drums. Just one more. Just one more and then I would be done.

"This isn't hunger. Not even fledglings need to feed this much. Four nights in a row now, Megan. Even you must see this for what it is."

"Which is what?" I snapped, but my head was pounding so hard that I had to stop for a moment, feeling a dizzy hue cloud my vision.

Immediately, Harper dragged me over to a darkened shop doorway, leaning my back against the window and holding me steady so I wouldn't fall to my knees.

"See?" he hissed. "You're exhausting yourself. This all-out mission to slaughter half of London isn't fooling anyone, least of all me. You think I don't know what this is all about? You think I don't know you by now?"

I tried to push on his chest, but it was a useless endeavour. I could barely stand up straight, let alone fight him.

"You can't run away from this, Megan."

"I'm not trying to," I said weakly.

"Yes you are. Do you think that by killing as many as you can get your hands on that somehow this will make this all go away? That it will prove you're not what Lucius says you are?"

I groaned and clutched at my throbbing temples. My skull was cracking, I was sure it was. It was cracking and falling apart, just like the rapist's had beneath my fingers.

"You have to stop this now, okay?"

"I can't," I whispered, turning my face to the window and pressing my head against it, letting the cool glass soothe the pain that thundered like a maelstrom through my head. "I can't stop."

He grabbed my chin roughly and pulled me to face him. "You have to. Do you understand? You have to. Do you know what happens when a vampire gives in to the hunger completely? Do you know what happens when they cut out all rational thought, all will-power and all self-control and give in totally and utterly to their desire for blood? It's like some kind of primeval order taking over. You get to the point when you don't even know who you are anymore. You become instinct and hunger and nothing more. You become little more than an animal and you don't care who you kill. Everyone is fair game to a Feeder. Man, woman, child. You will rip them all apart regardless and you won't even care. And once a Feeder, always a Feeder. It's unstoppable. You go down that road, Megan and you will never come back, do you hear?"

"It has to be better than this," I moaned.

"Don't ever say that!" he gasped. He drew back his hand quickly as if the touch of my skin had burned his fingers. "Nothing is ever worse than being a Feeder."

"Then tell me how to stop this, Harper!" I pleaded, slumping back against the window, tears stinging my eyes. "Tell me how to stop them because they're killing me. I can't take it anymore. They're so loud and there's so many and every day that number grows. I can't think straight. When I'm awake they're there. I can't sleep because that makes it worse. I'm so tired all the time and I'm so fucking scared. Feeding is the only thing that keeps them at bay and if I can't do that, what the hell am I meant to do? What do I do, Harper?"

I crumpled to the ground, tears now streaming down my face as I looked up at him, imploring him to help me, to do something, to say something.

"I don't know, Megan," he whispered aghast, shaking his head. "I don't know."

I pulled my knees up into my chest, wrapped my arms around my head and sobbed until my throat was raw.