My name is Cassie. I'm an Animorph. I am one of six kids fighting a war against the Yeerk invasion of Earth, using our power to morph into animals. Yeerks are alien parasites that look like little grey slugs; they can enter your ear canal and spread themselves over the crevices of your brain. And if they do that, your body belongs to the Yeerk. You can't scream, you can't twitch. You can't move a single muscle if the Yeerk doesn't will it. Nor will anyone around you notice something wrong, because your Yeerk can access your memories and make you act exactly how you always act.

I can't tell you my last name. If I did that, the Yeerks would find out who I am. They'd capture me and force my head under the sludge of the Yeerk Pool hidden under our town. They'd have a Yeerk slug crawl onto my brain through my ear. They'd turn me into a human-Controller - one more slave for the Yeerk Empire.

But something that was so easy to forget was that not all Yeerks were bad. Some Yeerks out there objected to the taking of involuntary hosts. These Yeerks believed that their relationship with a host should be one of voluntary symbiosis, not one of enslavement. Those Yeerks had come together and formed a resistance called the Yeerk Peace Movement.

I had a Yeerk from the Yeerk Peace Movement in my head right now. Her name was Aftran 942.

((Aftran?)) I said into my shared mind. ((Don't you want to take control?))

((Oh, Cassie, I couldn't!)) Aftran said. ((It's your body, Cassie. And you've done so much for me already!))

Cut off from the Yeerk pool, Aftran had no way to feed on the Kandrona rays of the Yeerks' native sun. Her first action upon connecting to my brain had been to ask me to kill her and spare her from the pain of Kandrona starvation. I hadn't granted her that request. There had to be another way, I'd told her. There just had to be.

Besides, Aftran had two more days before starvation set in. Until then, I wanted her to enjoy my senses as much as she possibly could.

((I don't mind you controlling me, Aftran,)) I said to her. ((Not now.))

I'd spent the last hour or so staring at my homework in my bedroom, without writing a thing onto the page. I guess I was too drained from the day's events, and too apprehensive as to what I might soon have to do.

((Are you sure, Cassie?)) Aftran said. ((I already have your senses. Your senses are enough - really!))

((I'm sure, Aftran,)) I said.

I wasn't sure at all. I could feel my heart starting to race at the mere thought of her taking over. I didn't want my heart to be racing. I wanted Aftran to be able to enjoy this moment, free of guilt. I wanted the last days of Aftran's life to be happy.

'Just…do it,' I whispered aloud. 'Please.'

And just like that, my body was no longer mine. Every single muscle I had was no under the control of Aftran 942. I couldn't possibly have struggled, even had I tried. I was the host body of Aftran 942, to be used precisely as Aftran wished.

It wasn't the same as being an involuntary human-controller, of course. I knew Aftran wouldn't abuse the power she now had over me; I knew she wouldn't force me to do something I didn't want to do. But that knowledge wasn't enough to take away my fear completely. Much as I tried not to, I couldn't not think of the ways Aftran could hurt me right then if only she decided to. I imagined my fellow Animorphs being ambushed and dragged to the Pool, screaming as their freedom was taken away from them forever more. I imagined the same thing happening to my parents. I thought of all the memories Aftran could torture me with: memories of saying unkind things to people I loved, memories of any and all bad things I'd ever -

((Cassie, are you okay?)) Aftran said. ((I can give you control if you-))

((No. Stay there,)) I said, rather more forcefully than I'd intended.

Aftran had been just like the others, once. When I first met her, she controlled the body of a young girl named Karen. She'd kept that innocent little girl as her personal slave. She knew better now.

I'd thought that all Yeerks were evil once. I'd that that they were simply the Enemy: that they were just monstrous unfeeling slugs who deserved to die. I knew better now.

We both knew better now - hence how I found myself doing what I now was doing: valiantly trying to persuade a body-controlling alien to actually control my body.

((Okay,)) Aftran said. ((I'll stay.))

At that point, she moved my over to my bed and flopped my body down on top of it. She squeezed the covers with my hands, taking the time to enjoy their softness, and stared up at my roof as she did so. She then proceeded to slowly scan my eyes around my room, drinking in all the details there were to see: the painted walls, the colourful carpet - and the books on animal surgery still on my bedside table.

After a time, Aftran sauntered over to my window. She opened it wide, taking in a breath of cool fresh air. She looked out to the forest outside my home and to the setting sun beyond. She didn't speak to me, but I could feel her every emotion: the joy of having a human body with its human senses, and her gratitude to me for having granted it one last time.

Right then, all of this just felt right. It was right that Aftran had the chance to see this beautiful view through my eyes - our eyes. It was right that she would spend her last days in my human body, away from pain and imprisonment. It was right that I was able to feel the emotions she felt - that I too was able to take pleasure in such simple things as my access to human sight.

And I knew she wouldn't hurt me. I knew she wouldn't do anything I didn't want to her to do. I'd known that before, of course - but I truly believed it now.

All of a sudden, a curious sound escaped our shared mouth, like a gasp crossed with a chuckle. Aftran brought a hand to our face. She flexed and curled our fingers over and over, twisting our hand this way and that as she did. She stepped us away from the window and started to swing our arms back and fort. Then, she spun us round and round where we stood, letting our arms swing wide, our shared face beaming the entire time.

((Cassie, this…this…this is amazing!)) she said.

((What is?)) I said.

((Just…just all of it!)) she said. ((Your body, your senses, your…everything!)) she said. Just then, she did another little twirl, seemingly heedless of anything in the room around her. ((I've never…I've never felt like this,)) she said. ((I've never…I just haven't.))

She was making no sense to me whatsoever - but she was undeniably happy.

((It's just that, I feel like I'm…home!)) Aftran suddenly blurted out. ((I'm home!))

And with that one word, I began to understand.

I thought back to my time as a Yeerk in the Yeerk Pool. And as soon as I'd touched down into the sludge, I'd been overwhelmed by the safety and security and rightness of it all, surrounded as I was by my brother and sister Yeerks. My Yeerk mind was telling me I belonged right there, in the warmth of the Yeerk Pool sludge, even as my human mind urged me otherwise.

Was that how Aftran felt right then: safe and secure in a host who wanted her?

((No, Cassie, this isn't the same at all,)) Aftran said, reading every thought I had like an open book. ((I feel like I've been given eyes for the very first time, all over again! The Pool is just…the Pool,)) she finished weakly.

((What?)) I said. ((But…))

But I'd felt so good when I'd entered the pool as a Yeerk. Did Aftran really not experience the Pool the same way I had?

I felt Aftran probe my mind then, as though she was about to search my memories. I tensed up mentally, bracing myself…and relaxed once I realised Aftran was going no further.

((May I?)) she said.

I gave a silent mental nod, relaxing a little more.

I kept quiet as Aftran went through my memories of being a Yeerk. She focussed particularly on those memories of me entering the Yeerk Pool: of the sheer satisfaction of soaking up the Kandrona surrounded by my Yeerk brothers and Yeerk sisters. She replayed those memories several times in succession. She seemed utterly fascinated by it all.

((I remember this,)) Aftran said at last. ((This was how it used to be for me, when I was still young. Before I was assigned my first host.))

((Before you had eyes,)) I said.

((Yes,)) Aftran agreed. ((Before I had eyes.))

She took another moment to look around the various sights in my bedroom - and set my eyes on the homework that lay forgotten on my desk. I groaned internally. Homework was pretty much the last thing I cared for right then - but not doing it would simply complicate things for me later.

((I could do it,)) Aftran said. ((Shall I?))

((Yeah,)) I said. ((I you want.)) Which, I could tell, she did.

She finished the whole thing in just half an hour. Every minute or so, she called on the necessary knowledge stored within my brain; she probed my mind gently each time, just enough for me to notice, and then drew on what she needed after I'd given my silent ascent.

And every little thing Aftran wrote down, I understood immediately. All the necessary knowledge had already been there, I realised, locked away in the recesses of my brain; Aftran was merely unlocking the knowledge, and getting that knowledge out onto the page.

((Thanks,)) I said once she was done. I could have said more of course but, with our minds as close as they were just then, it hardly seemed needed.

Just then, Mom shouted me from downstairs. 'Cassie!' she called up. 'Dinner's ready!'

Aftran turned me towards the direction of her voice, but otherwise made no moves. ((Cassie?)) she said. ((Can I…can I stay in control a while longer?))

I thought of how much enjoyment Aftran would get from the taste and the smell of our meal. I thought of just how greater her enjoyment would surely be if she was doing that smelling and tasting herself. And I answered her without the slightest hesitation.

((You just stay in control as long as you want,)) I said.

That night, we snuck out of my house once we were sure my parents had gone to bed. Aftran had wanted to try out some of my morphs while she had the chance and, naturally, I'd accepted. We galloped over the field outside my house as a horse. We ran through the trees of the nearby forest as a wolf, then flew back over those same trees as an osprey under a starry sky.

((I could get used to this,)) Aftran said, flapping our powerful wings.

((Me too,)) I said.

I meant it, too. I'd spent almost the entire evening under Aftran's direct control - but as a partner, not as a slave. I'd had her go through my memories - but only specific things, and only with my total consent. I trusted her completely to not hurt me in any way.

I'd have happily hosted her forever more, had circumstances allowed it. I wouldn't have wanted her to control my body always, of course, but I'd have certainly been happy to share it - as, I was sure, would she.

((I wish you could stay,)) I said to her suddenly.

((Me too,)) Aftran said.

We were reaching the end of the forest now. Aftran lowered our shared body to the ground, and then landed on the field outside my house. She demorphed and then flopped onto the grassy ground in my human body, letting my eyes wander over the stars.

((I've never had a voluntary host before,)) Afran said after a time.

I wasn't really sure what to say to that - so I said nothing. Aftran must have known was I was thinking right then, though: about how Karen had experienced things no adult should have had to experience, let alone a young child. And that was just the host I knew about; I didn't know how many there had been before.

((There were two,)) Aftran said. ((Both Hork Bajir. Both involuntary.))

She let Karen go, I reminded myself. She changed long before today.

((I used to think the best hosts were broken hosts,)) Aftran said. ((The ones who just…didn't talk.))

((The ones who didn't resist,)) I said.

((Yes. That,)) Aftran said. ((When I first entered Karen, I wanted nothing but to go back to the Hork-Bajir hosts and to the silence. And yet…I couldn't bring myself to silence her. I could have done, but…))

I said nothing. I was trying very hard to think nothing right then, as a matter of fact.

((…But I didn't want her to go quiet,)) Aftran said at last. ((Not really; not after the first day or so. It seemed so strange: I couldn't bare her wailing, but I knew I'd have bared her silence even less. I didn't want a quiet host after a few days with Karen. The thought of it just felt…wrong, somehow. Like I'd have I'd have been…been…))

She just couldn't seem to find the words.

((You'd have been alone,)) I offered. ((You'd have been all alone in that host's head.))

((Yes, that's it, I think,)) Aftran said. ((And I didn't want to be alone. Not again))

Even if it meant listening to Karen's non-stop mental sobs.

((Humans are so strange,)) Aftran said suddenly. ((All that time, she wanted freedom. And she was so grateful when I promised to release her. And yet, she got so upset on our last morning together. She was honestly sad for me, for what I was about to lose. Even after all I'd done to her.))

((Karen was always sad for you,)) I said. ((Even before you changed.))

((Yes, you're right,)) Aftran said. ((She was.))

Aftran sat me up slowly, and then pulled my arms into a loose self-hug. The wind was starting to pick up now, and I shivered a little under my morphing outfit. My eyes were starting to feel heavy, too, and I knew we would need to go to bed soon.

((Thank you, Cassie)) Aftran said. ((Thank you for showing me a better way.))