My name is Elizabeth. Most people call me Beth. I can't tell you my last name, much as I would like to. I can't tell you any details about me, in fact, save for the things that are general enough to not trace back to me. Because to many people, I am something that is to be feared and hated: a voluntary host to a sentient alien slug called a yeerk. Yeerks are parasites - that's what most people call them, anyway - who can crawl through your ear canal and take over your body and brain. Once a yeerk is in your brain, you are entirely at their mercy. They can move your body as they wish, leaving you a hapless observer in your own head. They can access every last one of your memories - and even force you to relive those memories, if they so choose.

Yeerks don't need to be parasites, though. My current yeerk, Calgiss 5631, is anything but a parasite. Calgiss is the creature that lets me vividly relive my best and happiest memories, as though I'm there living them all over the again. Calgiss is the reason I can go out with friends, watch movies, read books, eat good food. Calgiss is the reason I can go though College without needing someone to push me around in a wheelchair all day. Calgiss is the reason why - at least on the outside - I'm able to live a normal and independent life.

But then, I of all people should know that yeerks can be parasites. Yeerks are the reason I need Calgiss 5631, after all. You see, several years ago, yeerks attempting to invade our planet in a secret war. The yeerks were held off for years by the Animorphs, a team of five human kids and one alien kid with the power to morph into animals. Eventually, the yeerks were revealed and the Animorphs won: they freed the yeerks' hosts and destroyed the Yeerk Pool hidden under our town, where yeerks needed to return to every three days to feed on the Kandrona particles of their native sun.

And through almost all of that time, I was an involuntary host to one yeerk after an other. I was a human-controller - a slave to my yeerk masters. I was just one of many that the Animorphs were fighting with their lives to free.

'Beth, you need to know this,' Tom Berenson said. 'I love you. I just…really, really love you. You're the only only I've ever wanted be with!'

We were alone in the school gymnasium - me, with my freckles, alone with the top player of our high school basketball team! It was too good to be true - and was getting better and better my the second! Tom was resting his hands on my shoulders, slowly and gently pulling me into an embrace, bringing his lips to touch my lips and-

((Okay! Okay! I'm sorry!)) I said. ((There! I said it! Now stop it! I said sorry! Stop it! Enough!)) Almost immediately, that old childish fantasy of mine faded away. ((There. I said sorry,)) I said. ((Satisfied?))

((Very,)) my yeerk said. ((Now behave.))

It took me a moment to realise where I even was: in a history class at my school, sitting in the back row. When yeerks replay memories - even memories of fantasies - those memories come out so vivid that you don't just remember them: you see and do them, all over again. It's not so unlike dreaming, actually, except you only ever wake up if the yeerk wills it.

I'd been a host to a yeerk for just a few months. I'd joined the Sharing - a yeerk cover organisation - hoping to make friends. I'd been approached about becoming a Full Member, and led away to a little office where I was told the truth - or at least, a heavily sanitised version of the truth. I'd panicked upon being told about the yeerks. I'd turned and ran.

The yeerks were prepared to deal with those who ran. They didn't take kindly to those who ran.

((Oh, and that kid?)) my yeerk said. ((He's becoming a Full Member tomorrow. Might even turn out voluntary, knowing his type.))

I'd been made to eat with Sharing members over my lunch break that day - partial members, without yeerks, not Full Members like me. Someone had asked about becoming a Full Member, and I'd made the critical mistake of trying to warn him. I'd struggled madly with my yeerk for control, even managing to twitch my mouth a little before she managed to regain her hold over me. She'd told me to say "sorry"; I'd refused. She'd then started playing that old Tom daydream on a loop until I finally relented.

Yeah, I thought. That's totally fair.

((So,)) my yeerk said. ((I daresay that little rebellion of yours achieved nothing.))

((I moved my mouth,)) I said. ((That's an achievement, isn't it?))

((I suppose,)) my yeerk said. ((Oh, and you got to spend a whole twenty minutes with the boy of your dreams. That's an achievement too, right?))

((You know what?)) I said. ((Yes. Yes it is.))

My yeerk went quiet for a moment; I guess she hadn't counted on me getting testy quite so soon. In front of us, my teacher droned on and on, writing about something or other on the blackboard; he might as well have been speaking in a foreign language, what with how little attention the two of us were paying.

((I only did that because you rebelled, you know,)) my yeerk stated matter-of-factly.

((You didn't have to do it,)) I said. ((You'd already gotten control.))

((Well, perhaps now you won't do it again,)) my yeerk said.

((Not if you actually pay attention, I won't,)) I said.

My yeerk's hold over me had been loose. Usually, my body was almost completely numb when the yeerk was in control; at the time, though, I'd been able to feel the food I was holding in my hands. That's how I'd known I'd be able to rebel; that, in turn, was why I'd done it.

More silence from my yeerk. ((I suppose I got careless,)) she said. ((Satisfied?))

((Very.))

My yeerk went quiet again, as she jotted down the notes that had accumulated on the blackboard. She scribbled quickly, finishing moments before our teacher wiped the board clean to start anew. I, for my part, continued to not pay attention, too busy basking in the latest of my little victories.

((You know, most hosts would go quiet after something like that,)) my yeerk said. ((And they certainly wouldn't feel smug over it.))

((I guess I'm not most hosts,)) I said. ((Problem?))

((Problem? Don't be silly,)) she said. ((You're a slave. I control you totally. I know everything you've ever done and I know every one of your little fantasies.)) She noted down something my teacher had just said. ((If you want to feel smug over our little word games, you go right on ahead.))

((As you command,)) I said, making it sound as theatrical as I could.

I was honestly enjoying myself, strange as that might sound. My yeerk must have been enjoying herself too on some level, as she could have effortlessly silenced me had she truly wanted it. But then, if she did that, then she'd have had nothing to distract her from the boring class going on in front of her. And this particular class was always boring - that, at least, the two of us could agree on.

((All of your classes are boring,)) my yeerk said. ((You humans learn everything so slowly. And they teach you so much that just isn't needed.))

We'd had this discussion before. We'd had it many times, in fact. To my yeerk, anything that didn't have some practical purpose was useless to learn. To my yeerk, things like mathematics, science and engineering were needed; things such as art, geography and history - or at least, human history, were very much not needed.

((Dance isn't boring,)) I said. I knew my yeerk liked dance class because she never complained when we were in dance class. ((Geography isn't boring,)) I said. Much as my yeerk complained about geography lessons, she only seemed to do it while not sitting in geography lessons. ((English isn't-))

((But you hate English,)) my yeerk said.

((But you don't, do you?)) I said. She liked the books and the poetry, even if she hated all stuff about grammar. After all, she never complained about the books and the poetry.

More silence from my yeerk; another victory for me. Though, quite why she felt the need to go silent over that, I hadn't figured - not just yet. My yeerk went back to scribbling down notes, while I went back to simply not paying attention. Why pay attention to this, after all, when my yeerk was doing all the work anyway?

It was times like this, when we just playfully bickered with one another, when I wondered what would be like to be a host had there been no Empire. What would I think of having a yeerk, I asked myself, if it had just been myself and the yeerk and no wider invasion to worry about? What if there had been no involuntary hosts to see dragged to and from the pool? What if there had been no threat of friends and family being infested at every turn?

I knew my yeerk more-or-less needed a host, helpless as she was in her natural slug-like state. I knew she loved having access to my human senses; she'd never admit it, but I knew she loved it. Why else, after all, would she constantly stop to stare at my surroundings whenever we weren't around people I knew? Why else would I occasionally feel emotions of bliss and awe emanating from her, over nothing more than my empty bedroom?

Why couldn't they have just let us come to them? Why did yeerks have to be so…so…imperial about everything?

I felt my yeerk touch my mind for a moment, as though she was getting ready to say something. Then she apparently thought better of it, and remained quiet for the remainder of the class.

I think we were both glad by the time the bell rang. My yeerk hurriedly packed my things away and then joined the throng of students making their way outside. She found Helen, my best friend, waiting for me outside the school gates.

'Heya,' she said as I was made to approach.

'Hey, I was made to say back.

Helen, in many ways, looked a lot like me: slightly overweight, and with slightly freckled skin. We'd been friends for years, initially brought together by our mutual lack of friends from elsewhere. We were both prime Sharing material, for sure; I'd even innocently invited her to join me, back when I'd first decided to go.

((Two losers against the world,)) my yeerk said. ((How inspiring,))

((Three losers now,)) I said.

((Hey!))

In the world beyond my head, Helen and I had started the walk home. It was the perfect day to be walking: a faintly breezy Spring day, neither too hot nor too cold. Trees with fresh green leaves rustled gently in the wind, with the odd car passing us by as we headed down the sidewalk. A hawk circled lazily in the air.

'…Anyway, it's awesome. You should really read it,' I heard Helen say. I was fairly certain I knew what she was talking about, even though I'd only just started listening. 'I could lend it to you if you like.'

'Yeah, please. Thanks!' I was made to say back. 'Oh, did you hear about…'

It dawned on me quickly that I could actually feel the breeze. That meant my yeerk was once again only keeping a loose hold over me. I could probably have struggled for control right then if I'd wanted to, if only briefly. But I didn't want to right then, and my yeerk knew I wouldn't want to right then, because the walk home with Helen was one of the times of the I could pretend I was still myself: that it was me who was saying all those things I would naturally say, that it was me walking home with my best friend, that I wasn't in fact playing host to an alien invader from another world.

'Why don't we go see a movie tomorrow?' Helen said suddenly. It would be Saturday tomorrow - no school. 'Or maybe we could hang out in the mall, or something?'

'Sorry, can't,' my yeerk made me say. 'We're doing a Sharing trip that day.'

'The Sharing?' Helen said. 'Again?'

'Yeah!' "I" said, sounding perfectly happy with it. 'We're going to the Gardens for a day out. There's going to be loads of new members there, and…say, why don't you come? I'm sure you'd like it.'

I realised right away that my body had gone numb. Oh no.

'Oh, I don't know,' Helen said. Yes! 'I've never been to the Gardens.'

'My neither, actually,' I was made to say. 'But I hear there's a lot to see there, and it would be fun if we were both there, so…what do you think?'

'Well…' Helen began.

Within the prison of my own head, I was in turmoil. ((No! Please don't!)) I wailed into my head. ((You don't need her! Just leave her out of it!))

((Quiet! I'm busy!))

'Well, okay,' Helen said at last.

((No! No! No!))

'Great!' my yeerk said in a perfectly cheery voice. 'We're leaving from the school at eleven, so why don't I come round to your place at…'

I had to warn her! Perhaps if I twitched a finger, or maybe if I moved my mouth for a moment, or-

I attacked the yeerk's control with all the effort and force I could muster. My arm quivered a little; nothing else moved.

'Hey, you okay?' Helen, said.

'Yeah, fine,' my yeerk said. 'Just a bit cold, I guess.' ((You stop that or be punished!))

I stopped immediately. That silly business with the Tom daydream hadn't been a real punishment; I knew all too well what a real punishment from a yeerk entailed.

'Well, looking forward to it, I guess,' Helen said. We were right outside her house by now. 'See you tomorrow!'

'See you!' my yeerk called back. Then we parted ways.

((Go back to her!)) I said as she disappeared through her front door. ((Have us go out somewhere nice. Just…not to the Sharing! Anything but the Sharing! Please!))

((She's going to the Sharing tomorrow,)) my yeerk said, in a tone that left zero room for debate.

((But you like walking with her!))

((Doesn't matter,)) my yeerk said. ((It's my duty to recruit more hosts, and that's what I'm going to do.))

((Even though you don't like doing it?))

((Yes! I mean, no! I mean…stop! Just stop! I was assigned to you and ordered to recruit more hosts, so I am going to recruit more hosts. Got it?))

If this had been one of our bickering sessions, I'd have been "winning". This didn't feel like "winning". ((But you didn't need to-))

((Yes I did!)) my yeerk shouted. I'd have winced, had I been able. ((Yes. I. Did! Don't you realise what would happen if I let her go? Don't you know what they do to yeerks who commit treason?))

Wait, what? Treason?

((What do they do?)) I asked. That was just one of several questions I now had.

((They…)) my yeerk began. ((Look, I shouldn't even be talking to you about this. Just…just be quiet for a while - please?))

Please, I thought. That was a new one.

((Okay,)) I said, and then went quiet as asked.

My yeerk caught a bus for the rest of the way home, staring out of the window for the entire journey. She had me toy with my hair with one hand the whole way, the way I so often had done before.

((You're frightened, aren't you?)) I said at last.

My yeerk ignored me completely. To me, that was answer enough.